There's a few different ways I've found to try and help you find the right champion for you.
ARAM will force you to play all different kinds of champs. I've ended up buying champs I never would have otherwise simply because they were on free week and I rolled them up. Sometimes it's not enough to look at the abilities and say "No, I wouldn't like this", sometimes you have to actually play them to find out if they groove well with you.
Watch youtube videos of different champions. If the player is good with a champ, they'll show you exactly what a champion's ideal playstyle is. When you watch them play and go "Yeah, that's how I want to play this game" then you might have found your main.
Don't rule out off-builds. Sometimes building a champion AD instead of AP changes their playstyle around drastically enough to the point wherer they might as well be a different champion. I know a guy in diamond who mains AD
and AP
, and they play radically different than normal Malz and Koggles.
And if you do all that and you still can't find that one champion that speaks to your soul, that might be your answer. Maybe you're just not the type of person to have a main. Maybe you're the type of player that specializes in a number of champs instead of a select few. In a lot of ways, especially soloQ, that's better. It'll be more difficult for opponents to ban you out, you have more options open for counterpicks if you play draft, and you can branch out into other roles so you're not crippled if you don't get the role you want.