Warboss; Warbosses are mandatory if you plan on running a n infantry heavy army. They are our best CC HQ option, provide the Waaaagh! to allow us to move, run, AND charge like we used to be able too (For one turn, which is all we SHOULD need in most cases). He also provides a S10 power klaw, which is highly valuable in our army. The relics he can take have made him almost auto include (Especially the Lucky Stikk for the +1 Weapon Skill to his entire unit, and rerollable To Hits, To Wound, and To Saves with a drawback). He can take Mega Armor for a 2+ save, so he can either lead a slow Boy squad or a squad of Mega Nobz so he can tank some hits with his rerollable 2+ armor save (Just watch out for Ap2 guns heading their way, though stick him in a Trukk or Battle Wagon and screech up the board with his unit)

A+

Painboy: Another near mandatory HQ unit. While they are basically Nobs, they give FNP to whatever unit they are joined with. This is HUGE for Orks, as we have T4, making it very easy for us to just shrug off small arms fire, taking literal anti tank weaponry to kill us with no chance for survival. For 50 points, you can make a 30 Boy blob and the Warboss leading it insanely durable...it's a steal. (These guys are VERY easy to convert from a Nob model as well, so you can save money by making your own instead of spending 20+ bucks for one off GW)

A++

Big Meks: A much beloved HQ that has gotten a little better and a little worse. He's still cheap at a base 35ish points, but can take the much loved (but highly random, and thus competitive) Shokk Attack Gun, a potentially high powered Large Blast weapon that can either obliterate whatever it shoots at or merely tickle them depending on your dice rolls. More importantly, they can take Kustom Force Fields, which provide a 5+ invulnerable save (Against shooting attacks) to any model within 6" of him. This is pretty awesome, especially combined with a Painboy, giving a 5+ Invul to the inevitable hailstorm of bullets and shells coming your way, and getting a 5+ FNP on top of that to anything that doesn't Instant Death them. BMeks can also take Killsaws instead of normal Power Klaws. They are better in the fact that they provide Armor Bane for 2D6 on your Armor Penetration, making them even better at destroying vehicles. Big Meks can be a high utility HQ, and can also be fitted with Mega Armor to lead Mega Nobz along with a Mega Warbsos if you really want too (But Big Meks can get expensive points wise if you're not careful)

B+

Honestly, the rest of our HQs are more if you want to play fluffy lists. Zagstruk if you want to play a lot of Stormboyz, Badrukk if you want to play a lot of Flash Gitz, Weirdboyz if you want to dabble in Psychic powers. Though none of the latter are very competitive HQs as they have little customization options, and really only work with specific units.

Boyz: Boyz are our basic and most useful Troops choice. You can take them in squads as small as 10 or as large as 30, making them useful for various things. You can tuck a small 12 Boy squad into a Trukk for a super fast moving assault unit. You can put up to 20 in a Battle Wagon for a slower but more durable assault unit that might actually make it to the other side in one piece. Or you can take 30 on foot with a Warboss and Painboy to slog their way up the field and hope they can weather the storm. (They might, if you provide enough other threats to detract fire from them)

Boyz are fantastic and are cheap to field. They can hold objectives, they can tarpit, and they can bring a Nob in their squad as an upgrade who can bring along a Power Klaw, which is the key to Orky success. (Power Klaws solve a lot of our issues). Boyz get a lot of attacks (up to 4 on the charge if you take them with sluggas and choppas) and sit at T4, making them surprisingly annoying to wittle down.

If you give them Shootas for just 1 extra point, you get Boyz who can really unload a lot of firepower at short distances to wreck lightly armored infantry or drown even Marines in volume of fire. Shootas are Assault2, 18" guns, and though Orks are bad at shooting, even a 20 Boy blob of shootas is firing 40 shots...SOME of them are bound to hit and wound ;P

A

Gretchen/Grots: Ah, the little goblins. Grots are dirty cheap to field, and you can put them in blobs of 10 to 30, though for every 10 you need a Runt Herd, who is basically a Boy who is on baby sitting duty. So if you took 30 grots, you need 3 Runt Herds on top of that, for a total of 33 models in the blob.

Gretchen/Grots...are weak. They have very low strength and toughness. But their strength lies in how SMALL they are, and their "better than other Orks" shooting since they have BS3. Grots make great objective holders, especially if the objective is hidden properly. Remember, if your opponent can't SEE the Grots with their models, they CAN'T shoot at them. Sneaky little gits!

As for combat, Grots have a S3 pistol. It isn't much, though with their better BS, you should be able to get more hits in for more chances to actually wound, making them OK for fending off anyone trying to take your objectives. But the 12" range is pretty bad (Basic pistol range).

Grots can also be used for screening, as if you let them stand side by side in a line in front of a unit you want them to 'protect'. What this does, is if your opponent tries to shoot the unit they are in front of, the unit gets a 5+ cover save because they are shooting through intervening models. While a 5+ cover sounds worse than a 5+FNP or 5+ invul, it's drastically cheaper to provide. The Grots even protect the unit from a frontal assault, as your opponent would have to attack the Grots first, or move around them. The Grots can then soak up Overwatch by trying to assault first, or assault something that might hurt the Boyz, thus tarpitting for a turn or two to let the Boyz keep moving on.

While not super strong, they have uses for their low point cost.

B+

Tankbustas: These guys right here have almost become the golden goose of our Codex. Tankbustas, like most Ork units, don't cost a lot of points to field. They can only be taken in squads of 15 max, but they have such VALUABLE access to Strength 8 shooting that they become almost auto include in a competitive list. Costing under 15 points per model, they come with Rokkit Launchas and Melta Bombs, which is HUGE for such a low cost. Though like all Orks, they have only 6+ armor, so you really have to keep them safe! They now have Tank Hunter, which lets them reroll their Armor Pen rolls. While they can't cause vehicles to explode (Since Rokkits are only Ap3), they CAN bust open MEQ armor, which is also amazing. It should be fairly easy for a large squad of Tankbustas to glance most light vehicles to death in a single shooting phase. If they can't they can try to Melta Bomb them up close and personal! They also get Bomb Squigs (Up to 3 per squad) that have short range, but are very difficult to miss with (Missing only on a 1 I think) for a short ranged but highly reliable S8 attack on something. Tankbustas also give an extra 1 Victory Point if your First Blood kill is a vehicle, which is a nice little perk for such cheap models.

I highly suggest taking them in a Trukk. Though Trukks are fairly frail, they are VERY fast, and let Tankbustas get where they need to go and provide SOME protection. Battle Wagons are a tad too pricey, but if you have the points, you can tuck them into one for a very durable vehicle/MEQ hunting unit).

A+

Mega Nobz (Also known as MANZ): Oh boy. Where to begin. These guys are instantly better than they used to be. A bit costly to field, MANZ suffered from low Leadership and often were forced to flee as they couldn't use the old Mob Rule and could not be taken in large enough squads to use it even if they did. (And you don't WANT big MANz blobs...too slow, and make too big a target). Now, they benefit from Mob RUle so they are less likely to run, and can take a Bosspole to boot. These guys are our 'terminators' so to speak. Big, bulky Nobs in suits of Mega Armor. They rock Power Klaws and Twin Linked Shootas that you can turn into Kombi-Weapons if you wish. They may also take 2 Kill Saws apiece making them strict CC units, and making them more capable of wrecking tanks than before. It can be costly though.

MANZ suffer from lack of mobility. Due to Mega Armor, they cannot run at all, only getting to move 6" a turn. So, to amend this, most Ork players put them in Trukks. (See the theme? ) Trukks, again, are super fast and cheap transports. A lot of players call this a MANZ Missile. Some run 2 or 3, filling up their Elite Slots. It is best to take MANZ in squads of 3 or 4, sometimes with a Mega Armored Warboss. You don't want to over invest, and since their armor makes them Bulky (Taking 2 unit slots in a transport instead of 1), you need to keep model count low to fit in the Trukks.

That being said, if you get them into CC...they will ruin most anything in this game. The amount of S8 klaw attacks rip vehicles and infantry alike apart. Amazing models, amazing unit. Their drawback is lack of mobility without further investment.

B+