T2 LT is IMHO by far the best scout tank in the game for its tier. Although now they changed its gun .... so my opinion on it is dwindling. Still has speed but its cannon is worthless. However , its an elite tank so its XP is convertible and the percentage of free XP generated is greater. Same with the pz(f) and Tetrarch. All high scoring/paying tier 2s.
Those tier 2 tanks , and some of my tier 4s (elite American t40 , elite KV amd elite leopard) pay for the ability to run my high tiers. Tiers 9&10 , even in a win, you usually lose about 10k without premium.
Cant give advice on the American line. t40 and t2lt are my only Americans. I will say t40 with a full crew is beast mode. Nasty little bastard.
As for the Frenchie talk , well , I used some free XP (about a weeks worth) to grind up through the tier 5 medium (amx12). Its a fun little troll tank. I have the biggest cannon available on it and its pretty vicious. I can hit tigers and t29s for 10-15% and with 7 shots in less than a minute you can have some fun. Had a good match yesterday where I took out a t20 with the help of an arty. Kept tracking him , hitting him for dmg and bouncing about half the shells. Im a dozen or so battles away from the tier 6 (amx13 i think).