So I've been working on an armored company list as well and I 've had some experience fielding mechanized forces so I know how competent opponents will try to reduce your force and and out manuver you.

I'm not going to get into the allies thingy, because why field squishy meat bags when you can grind them under your tracks.

You should look into the doctrines for armored company, some of them can be devastating. For example ace gunner, which resembles the marginally useful sharpshooter infantry doctrine, except that rerolling the scatter die significantly improves the chances of a successful hit with a pie plate. Side skirts (+1 to side armor) mean plasma is almost useless (only the rear is now vulnerable) against main battle tanks. Overcharged engines mean an 18" move (definately couple that move with smoke) great for out flanking and grabbing objectives.

The main problem I have with the list below is that the mean armor values are too low. Hellhounds are great in support of a mechanized force but they will be the first targets for all your opponents midrange firepower (strength 6-7) and their side armor is vulnerable to strength 5+ (think heavy bolters and pulse rifles). Then your opponent will hit your bassies if he's got deep strikers, fast movers, or because you simply unable to hide them effectively. An opponent fielding any armor will also make it a point to fire all his dedicated anti-tank weapons at your vanquishers to keep you from killing his armor (battle cannons are poor anti-armor weapons). Oh yeah, what is your solution to terminators, obilterators, and other 2+ saving tank killers? Finally, just about anybody whose faced pie plates before will try to disperse to reduce their effect, do you have a direct fire solution to this?

A very important consideration in fielding an armored company is maintaining a shock and awe effect in your opponent.... leave as much as half of his weapons useless and then crush those that do threaten you before they can used to sinister effect against your paltry 11 wound army

I don't necessarily think my lists are better but they may handle these problems a little better.

Armored Company List V2
( 8 Tanks, (all 14/13/10) 6 pie plates (all rerollable), two Dedicated Anti-Tank)

Doctrines
Ace Gunners (reroll scatter direction die, or rolls of 1 to hit)
Over Charged Engines (additional 6" movement with diff terrain test)
Side Skirts (+1 to side armor upto 13)
Heavy Armor (Tanks may be in fast attack)

HQ
1) Leman Russ Vanquisher 100+185 (3HB)+53 = 338
    Ace Gunner, Side Skirts
    Track Guards, Extra Armor, Smoke

Elites
1) Destroyer Tank Hunter 65 + 170 +63= 298
    Side Skirts, Ace Gunner
    HK Missile, Extra Armor, Smoke

2) Destroyer Tank Hunter 65 + 170 +63 = 298
    Side Skirts, Ace Gunner
    HK Missile, Extra Armor, Smoke

Troops
1a) Leman Russ 155 (3HB) + 45 =200
    Ace Gunner, Side Skirts
    Extra Armor

1b) Leman Russ 155 (3HB) + 45 =200
    Ace Gunner, Side Skirts
    Extra Armor

2) Leman Russ 155 (3HB) + 45 =200
    Ace Gunner, Side Skirts
    Extra Armor

Fast Attack
1) Leman Russ 155 (3HB) +63 = 208
    Over Charged Engines, Side Skirts,
    Track Guards, Smoke

2) Leman Russ 155 (3HB) + 63 = 208
    Over Charged Engines, Side Skirts,
    Track Guards, Smoke

 V2 is harder to flank effectively as they are better armored, and the flankers can move 18" then pop smoke for a rush. There are three tank hunters so enemy armor is less survivable. In addition, the destroyers can kill almost any character outright even upto T5 and 2+ Save.

If all goes to plan (ha ha ha! that almost never happens) I imagine the Russes all opening up on enemy infantry. The destroyers eliminate high strength targets, and the Vanquisher picks on remaining high value targets. The flankers will rush forward to claim objectives/ quarters when necessary.

Necrons would decimate this force once in range, way too many glancing hits. Beware Terminators, Speeders, and Monstrous Creatures as they could do terrible things once they close to effective range (12-24"). Droppod marines with powerfists and meltas could rampage through your lines so don't give them the chance to get close enough, deploy appropriately.

@alarmingrick Demolishers would also work fairly well. I would add smoke and overcharged engines and run them two of them right up the sides of the board so that next turn there would be nothing out of range of them. Tank Destroyers can sit on the far corners of the board (72" range s10 ap1 blast) and use their bs4 (if aces) to hit on 3+... far less random, but also less likely to be in assault range of the baddies.