Feral Orks are tournament winners, though you really break the army by doing it, they are pretty top tier albeit boring.
Here's the rundown of what I like to do.
General Good Ork Stuff: 1.) Painboss w/ Cyborks in a Trukk. This is like a trukk mob, but better. It doesn't have a hidden
PK Nob, but with 9 Cyborks who are T5, S4, 5+
Inv, you get the job done. Also, it gives you a trukk mob without burning a
very valuable fast attack slot. This is huge since a lot of great things are in Fast Attack.
2.) Trukk Mobs. See above, they get stuck in and tie things up for your other boyz to march up the field. Many times for me, the game winner is having my Trukk boyz make it to turn 2 and being able to make their charge, if that can happen then my chances of winning go up exponentially.
3.) Buggies. Rokkit Buggies provide excellent Tank hunting that Orks need a lot of help in, and screening for Trukks if you don't have a good amount of terrain. Also Skorcha Buggies are cheap and extremely good for drawing some fire from the Boyz. A lot of times you'll see them do great things if your oponent ignores them on the first turn. Also, buggies in general are excellent last turn objective grabbers, they also always come with the Red Paint Job and Grot Riggers.
4.) Looted Vehicles. You can get a Leman Russ, a Demolisher, or an Indirect Bassy. In fact some clans let you take all 3.
5.) Boyz. Slugga Boyz to be exact. You could go with Skars or Ard boyz, but they die almost as easily as the regular boyz and if you can get any amount of Orks in combat you stand a great chance of winning, so I'm starting to take less Skars/Ard boyz and more regular sluggas. My footslogging Orks always come with 3 Rokkits as their special weapons, since you NEED anti-tank badly, and even if they don't have tanks their AP3 makes them great against
MEQ's for when they do hit. Oh, and every Ork mob has a Nob with Power Klaw.
EVERY ORK MOB.
Klanz I like:
Deathskullz are a pretty good clan, as they let you loot 3 Tanks, giving you the Orky trinity of the Bassy, Demolisher, and a Russ. I know it's unfluffy, but I'll take two minned mobs of Lootas with Mortars to meet the requirements for the klan, and then fill the list up with the above Ork good stuff as if it were a normal codex list.
Kult of Speed. I'm converting stuff to use for this Klan list so I can field either a codex, Deathskull, or a
KoS list with my Ork army. It is probably stronger than the codex list, but not as strong as it was previously as I understand it. It's a radically different play style and is actually pretty nice
IMO.