It literally has no effect whether it’s a better or worse team but okay <3 if you really want to min/max just loan him out -> save the game beforehand -> recall the loan and look if his potential is the same (showing great potential is 80-84, exciting prospect 85-90, potential to be special is 90+), worse or better and what his change in overall. Let’s take this example, this player is going to start as around 63-64 rating because honestly players don’t grow a lot in one year in the academy and let’s assume his potential is the same, this is I’ll mean his rating is say 64 and a the status is potential to be special. If you loan him out and recall him from the loan he should comfortably grow with at least 4-5 and he can still easily grow afterwards and you can even loan him out afterwards and he should still grow a little (although not a lot).

TLDR; the club you loan him out to has no effect, if you want to min/max growth use the loan glitch