In tanks.gg, click on the Tanks dropdown and go to Tech Tree. There you can find the total EXP needed to reach any tank, just hover your cursor over it. I found it really cool and decided to help you guys out by making a list of the cheapest and most exensive tank lines of every type.
CHEAPEST TANK LINES: (Heavy is the cheapest class)
OVERALL: 60TP (631,850 xp)
Arty: B-C 155 58 (776,970 xp), with the G.W. E 100 in a close second at 777,905 xp
Tank Destroyer: T110E3 (701,965 xp), with the T110E4 in a far second at 729,065 xp, and the Jg.Pz. E 100 at a close third with 729,505 xp
Heavy: 60TP (631,850 xp), with the AMX M4 54 in second at 638,015 xp
Medium: E 50 M (676,820 xp), with the 121 in a far second at 696,810 xp
Light: Manticore (704,955 xp), with the T-100 LT in a far second at 737,535 xp
MOST EXPENSIVE TANK LINES: (Arty is the most consistently expensive class)
OVERALL: ConquerorGC (829,235 xp)
Arty: Listed above, second place is USSR and USA at almost a tie with 817,540 xp and 817,445 xp respectively
Tank Destroyer: Obj. 268 4 (785,365 xp), with the Obj. 268 in a close second at 783,965 xp
Heavy: Type 5 Heavy (777,565 xp), over 140k xp higher than the cheapest and way way better heavy, the 60TP. Second place is the Kranvagn at 766,385 xp.
Medium: STB-1 at 818,785 xp (holy shit), thats even more than the T92 HMC… Closest second is over 60k away (K-91)
Light: Rhm. Pzw. (777,025 xp), second place is almost a tie with the AMX 13 105 (766,515 xp) and EBR 105 (765,155 xp)
Notes:
Depending on which heavy line you chose in the French tech tree, you could have a difference of 105,500 xp
With the xp required for the ConquerorGC, you could research all Tier 7 British tanks and still have 80k left over.
Japan needs to calm the fuck down with their xp requirements
Other than the #1 light, the cheapest lines are pretty meta vehicles. Not a bad idea for impatient new players.
Source: https://www.reddit.com/r/WorldofTanks/comments/lxmopx/i_did_some_research_on_tanksgg_and_found_the/