Whats yours?

[Tankbuster]

Easy with the thesis man.
(Take it with a grain of salt, will'ya.)

[Mad hatters in jeans]

My favorite faction is probably Wermacht. I love their adaptability, and how they make use of fewer but stronger troops. On the whole, I find Blitzkrieg to be somewhat OP (at least in the vanilla game) thanks to invisible, super-grenade throwing, double-panzerschreck-wielding elite stormtroopers and perhaps the best anti-infantry tank in the game (StuH). They also have my favorite tanks, the Panzer IV (looks badass with those armor skirts!) and the Tiger.
My second favorite is a tie between American and Panzer Elite. I find the PE to require a good understanding of the map and the enemy faction, thus making them harder to learn but all the more satisfying to use. In truth, hardly anything can stand up to fully maxed assault grenadiers, especially if you back them with a munitions- and infantry halftrack. Americans are great for their versatile forces, but often they seem to rely too much on spamming Rangers. The caliope is one of my favorite artillery pieces, despite their effectiveness being somewhat questionable. The american Reward units are a right arse, though, with the AC losing its MG and the Wolverine becoming a poorer pseudo-ambush vehicle. Meh!

My least favorite are the British, but that's not saying much. Generally, what ruins the Brits for me is their lack of any real AT-weaponry. Yes, they have a nasty emplacement, but it is expensive as all hell, cannot be moved and takes up about ten times as much space as a regular AT gun. Their slow infantry gives them a boring early game for me, as I rely mostly on just running my Bren around trying to cut off enemy pioneers while my troops saunter lazily towards their destination. Using their Churchills are quite fun, though, especially when you order the croc to hull down in the middle of their base facing their HQ. Hilarity ensues.

I've yet to play enough EF to really get a good grasp of the SU, but they remind me a lot of the Imperial Guard from the Warhammer 40k universe - a ton of cannon fodder troops, an officer surrounded by bodyguards who lead the troops into battle and some truly magnificent tanks. On my part I have yet to learn how to truly appreciate the light russian tanks, as they seem to lack the MG I'd want to deal properly with infantry (which is the role of a light tank if you ask me). But I can see myself getting to love them, at least on the same level as the PE and Americans.

This was a long reply. Oh, man.

Not too long post though. nice to see your reasoning as well.
the soviet light vehicles can give  PE player a headache.

[Cranialwizard]

My favorite has got to be the Wehrmacht, but not hands down. I am most familiar with the Wehrmact, and they have so many options when it comes to divisions such as AT, Arty, Tanks, etc. Hands down they are the most versatile faction. Their flexibility when it comes to armor is also quite nice and this faction supports 100s of strategies. (To name a few, Piospam-T2, T1-T3 Blitzkrieg, Medic Bunker Grenspam, so on so forth)

Second favorite is a close run, but it ends up to be the Soviets. Their upgrade system is unique and they have a nice sensibility when it comes to tanks. The doctrines are also quite nice as well, and they have a nice array of upgrades to squads. This doctrine also supports a vast array of different types of strategies because you can build your buildings at any time (Similar to the PE) and your upgrades are pick and choose for global. (Also similar to PE)

I really do not have a "Least Favorite", I like all the factions, but I believe my weakest faction to me is the British. The commonwealth is too blobbed and static for my typical style of gameplay, I don't like putting my truck too close to the front... (You don't know how many players I've decimated in automatch by putting a simple MG near their truck with some volks, a bike, maybe a sniper, and a flame pio to kill the truck...) Their late-game armor, like the Americans, is also pretty lack-luster. Fireflies are a hell of a powerful but their armor is paper thin, Grenadiers or Tank Busters can punch through it like nothing. To me the most effective doctrine by far is the Royal Engineers for this reason.