Perhaps the following definition of the meta could give you some ideas on where you'd want to go? I'd be happy to help you narrow down to champions you might like as well.
Top lane: usually bruiser-style play where you get up close and personal with the enemy team
Jungle: focus more heavily on objectives and strategy than the tactics that your allies focus on
Mid: typically either assassins with high single-target damage or mages that deal massive AoE damage to entire teams
ADC: lots of farming early game to slowly spin up into an unstoppable death machine later on
Support: help your ADC get fed by fending off the enemy ADC and support's poke and generally "carrying the carry." You'll also be concerned with overall strategy, though in a different aspect than the jungler will.
Within each role, there are champions that have more poke, hard engage (that is to say, dive straight into the enemy team and don't look back), mobility, etc. For me, I've always thought mages were the coolest classes in games and I like the ability to absolutely blast people with damage as a glass cannon. As a result, I ended up maining Veigar (pretty much the definition of a glass cannon burst mage) and Xerath (an artillery mage). I play RTS games, so I thought I'd try things like Heimer, Zyra, Ori, and Azir. The first two didn't do it for me, but I love the latter two.
There's over a hundred champions. What sorts of things do you like? Obviously we can't give you all the answers, but we can point you in the right direction. You'll want to play some bot games to get used to new champions. Personally, I played several hundred bot games and played little PVP until after I was level 30, though now I play PVP exclusively. How much you play bots or PVP is up to you.