Might be a little late reply but still gonna say since I also play team games too. This is what I do and it works very well. Not sure how it'll do now with the new patch coming soon.
Commanders to choose,
Vanguard, Special Weapons, or Royal Arty
IS
IS
Tech grenades (should have 3 IS with ones you start with)
Upgrade post
I always start out with this regardless of what commander I choose. IMO it's a very great opening. 3 IS can be overwhelming for ostheer, especially with grenades. If you manage to flank MGs/Mortars and throw grenades, it can be devastating to them. Well timed grenades against OKW can also result in them losing squads, especially sturms early on where 95% of OKW just rush them into your face. Also Brits can tech grenades very early on the game without delaying their HQ upgrade which can catch enemies by surprise. I'm shocked lots of people don't use grenades as brits.
Vanguard
AT Gun
Bolster Squad
Sappers, sniper, both or neither, up to the player. (Highly suggest sappers for mine sweeping, mine laying, and repairs)
Forward Glider
Commandos
Build units as needed
Upgrade HQ
2x Cromwell
1x Firefly
Then whatever upgrade is one with warspeed lol
You get AT gun to deal with light armor they throw at you, then you bolster squad to beef up your IS. Give your IS 2x Meds and 1x with Flares. With this you're being very aggressive. When you're about to push, put flare IS in some light cover so they can get their sight bonus. Sappers also help with CQC and mine sweeping but sniper can also help deal with everything, especially with its critical shot.
By then you should be at 3 CP, so call in the glider somewhere safe and start using the officer on your attacks. He's very good at CQC and has nuke grenade. At vet 1 he can also call in a recon run which helps on attacking. Also has a "british ooorah" ability that effects nearby units and makes them move faster. Then you build commandos from the glider. If you managed to keep everything alive and vetted, you should be floating lots of MP, so I just build caches for my team.
Now I say cromwells because they are very good, sort of cheap, fast speed and reload,at vet 3 they move insanely fast and with warspeed they're just a crushing monster. You're being aggressive with this commander, no sitting still or building sandbags on VPs and just sitting there and please
NO EMPLACEMENTS.If enemy starts spamming stugs, get some sappers with PIATs. If enemy starts spamming panthers, build a firefly or 2.
I've only managed to use the Crocodile once because the enemy always surrenders or drops from the game before getting it ingame. It's a real good tank, and with warspeed it can be terrifying. You probably noticed I didn't tech weapon racks. I'd honestly would rather be chucking grenades at the enemy and using abilities such as officers recon, lay mines or save up for the strafing support ability.
uuuhhh I'll write the rest later for other commanders, its 2 AM atm and I go sleep. And I know my shit with brits, I was #1 lvl 20 in 3v3,4v4 with randoms and lvl 19 in 2v2 before leaving for the army. Now my rank gone

same with usf