have you played with tigers recently? they don't hold up very well, especially on the offense (hence the introduction of all the super heavy vehicles like the jagdtiger, elefant, kingtiger, etc.).
OH is easy to play because they have many unit types as you'd expect them: an AT gun with great penetration, an MG every other faction wants to steal, versatile long and short range infantry, and a sniper that isn't retarded. they can be trouble for new players because you can't spam one unit and win with them... you have to play balanced combined arms to be effective.
SU is probably the best for new players because the six man squads make unit retention just a little easier. they're also flexible and not too wonky (I can't imagine just jumping into this game cold and trying to learn OKW or UKF).
USF are decent but have to be played a very specific way... i.e. very aggressive with good micro from start to finish. when you play USF you're constantly trying to react to what your opponent is doing or might do instead of imposing your will on them like you can with SU, OH, or OKW (and in mid game with UKF to some extent).
it honestly all depends on style. i have a buddy who doesn't micro well and loves to turtle... UKF it is. in a team setting he can still be super helpful. i don't think he plays 1v1s.
