yorick is boring as hell. His entire play style is throw ghosts then run away. At no point in the game have I enjoyed that bastard.
Now for some people that are actually fun. Singed, trundle, malzahar, vi, voli, poppy, and as much as I hate the broken blind bastard: lee sin.
singed: There is just something satisfying about running around throwing people and spreading a fartcloud everywhere. He's not quite there but he is pretty close to udyr in his ability to just run forever.
Trundle: Just picked him up a couple days ago and to be quite honest he is amazing. Thunking the enemy into submission with his club any time they decide to come near you without bringing half the team. The simple fact that he can pummel the entire enemy base while they try to push is quite honestly intoxicating. Incredibly fun. Also if you happen to be a jungler he can run the old route without popping a single pot until double golems/gromp depending on which side.
Malzahar: I'm just gonna be honest here, I suck at this game. I mean I'm really really bad at this game. Now that that's out of the way The sheer number of wtf and how the hell did I survive that moments I've had with malz is simply mind numbing. He's quite fun to play simply because his kit is fun but the situations you will get into just makes him that much better. Try him up top...Just don't first pick him in draft or ranked without banning trynd chogath and gangplank. Horrifying things happen to first pick malz.
Vi: Punch people in the snoz repeatedly. Good times were had.
Volibear: Righteous glory volibear is damn near inescapable. Just imagine this for a moment, you're pushing up a lane and everything seems fine and out of nowhere a homeguarded, rightous gloryed, snarling volibear comes zooming out of a bush at you. Your plan just went to hell and volibear is having a ball. rawr
Poppy: Somewhat in the same reasoning with malzahar with this one. Without a doubt my greatest moment in this game ever was on poppy. In a 5v1 sacrifice to save my mid laner and adc who got caught out I dove into the entire enemy team and just started swinging my hammer. I couldn't see my short yourdle self anymore as they were all right on top of me. I stalled out their entire team for over ten seconds with ult barrier and heal and even killed their adc and beat the rest of them senseless. For just a moment I was a shining golden leroy jenkins god. Also the two I saved came back after popping some potions and aced the clean up. It was amazing. Definitely play poppy.
Lee sin: I honestly don't have much experience with lee sin and I don't like the character but damn His sheer brokenness let me just hit random buttons and people started dying. It was an incredibly fun button mashing champ for me.
Now for some honorable mentions:
Twitch: Play him like a stealth assassin. It's nice.
urgot: qqweqqqqqqqqqqqqqqqqqqqqqq. That's pretty much it and yet it's quite enjoyable.
ap tristana: jump in, nuke, jump out or jump in nuke jump in nuke. Tristana is just a fun champion to play ^.^
Garen: How can you not have fun while doing the monkey? I mean really it's impossible.
ACHIEVEMENT GET: Red responds to my board
top
Full Crit 
top/mid
Full Crit 
mid
Full AP 
Never get tired or bored playing him.
--(last item lolz is a personal pref)
or 
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Trundle is really fun if you want a bruiser.
I don't know why, but he is just fun to play. My favorite ADC.
AP 
AP 
Too fun.
because she is fun af, but you don't like botlane so unless your willing to play her top/mid I guess I'd go with 
Is my favorite champ, and he can be played a variety of different ways... Try out AP Skarner top, it's a lot of fun. As is full-tank jungle. :D
. At 500 stacks just start yelling boom with every q. Cane will bring you respect...
You can either set up amazing plays with him or bait your team into oblivion.
