You can reply to this poll to explain your reasoning. Here I'll start off with my own favorite champion, Nami. I'll quote a part of a post I wrote earlier:

"She doesn't provide any auras, buffs or shields but I love using her Aqua Prison (Q) and ultimate Tidal Wave (R). Provided that you can anticipate your opponents' next moves you can absolutely secure kills or disrupt teams with Q, and a well-placed Q can completely turn the tide of a fight to your teams' favor. Tidal Wave is even better; you can use it to save a pursued ally from afar (I did this several times XO) or even catch (even kill, which I did) fleeing opponents. It is in a way a bigger, better version of Q. Nami's E, Tidecaller's Blessing, really buffs either your AD carry or anyone on your team that relies on the auto-attack, which really helps in teamfights or skirmishes."

That's the end of the excerpt, but I now appreciate her W ability, Ebb and Flow, a whole lot more since I wrote the post. Not only does it heal (you cannot have enough of those), but you can do some moderate damage against someone else. You can choose between 2 heals and 1 mini-nuke, or 2 mini-nukes and 1 heal. It's not a great heal in large teamfights but it is very good for the early laning phase; I can trade [damage] as Nami because I know that I will heal up most of the damage from the opposing bot lane and deal damage to them at the same time. It allows Nami and her ADC partner to be aggressive in lane and put the pressure on the opponent's bot lane.

Nami does not provide shields or auras, but as long as you play smart and aggressive (and that your team is good of course; any LOL player will tell you that you need your team to win), you can be a huge asset to your team without taking any kills. OK Imma step out of my soapbox now XD.

My favorite is Fiora, but I'm best with Volibear.

I love Ryze. I like playing mid and I love the way he scales. Goes from a crummy early game to doing a ton of damage and pretty tanky, it's a cool feeling.

My Favorite champ is Lux. I just love her long range harass and utility in team fights. Not a fan of support lux, all about that ap mid. I also love her ults cool-down, if you're doing well buy a Mejais or CDR and fire off that lazer every ~24secs

Been way into support recently, so Thresh is my main pick. Amumu is also lots of fun if I'm not ballsing up my Qs all the time. And fuck Teemo, obviously.

Ziggs. So much AOE, he is a beast at clearing a lane, and has a fantastic ULT. Also he is really fun to play, it's a blast leading targets and scoring great hits.

Invoker FTW.

Trundle pre-remake.

Katarina. Pop in, ult, pop out. Everyone is deeeeaaaaad.

I also really like Teemo, Malphite, Nami, and Caitlin.

Well I'm lame so Ashe.

I haven't played much LoL, but I've played the heck out of the original DotA and Frost Archer was my go to. Love me some Slow!

Great for a player like me who has lag, low FPS count and a bad video card to combat.