No such thing as an 'easy' league - you are racing against, potentially, the best people in LFS. If you can't compete, that's YOUR problem!!!
Which cars ARE you used to?
Are you sure you're a pro drifter? If you're new to LFS, and haven't driven all the cars properly then I doubt VERY MUCH you are remotely a 'pro' drifter. Sorry to burst your bubble, but I doubt 'competent' drifter would be advisable (although I haven't seen you drift, so feel free to post a movie/replay proving me wrong).
The league threads aren't confusing if you take your time, and go on word of mouth. If you like single seaters, then perhaps the OWRL is the one for you. If you like LXs then maybe the LXCC is for you. If you like TBOs then maybe the STCC is for you....
But since you've asked US to choose a league for you, I want you to compete and win the MoE league on your own. Thanks.