Cassiopeia. Easy champs get countered the easiest. Get really good with Cass, then tell me you have a losing streak.

that's generally how it's gone - i play a match, notice someone who got 2-4x my kills, try them for a bit. I only started playing like a week ago, and no particular champion stands out just yet, as i haven't looked through them all in a sense of trying to pick one for myself.

Watch some streams of high level players and watch what they do against certain types of champs. Either that or try to figure out for yourself how to overcome the weaknesses of champs you play. For example, Akali has her ultimate to bridge the gap, and with a rylai's crystal scepter, she slows the victims of her Q and ult and makes it near impossible to escape her. She has no trouble with ranged opponents at all.

easiest to play is probally ryze.

1) he is a caster so does a lot of damage
2) no skill shots
3) all you do is get a tear then build tank items that have mana (frozen heart, banshees, etc)

only thing is his early game, just stand back and last hit for a while since his early game kinda sucks

I gave it some thought - since as ForeverLaxx said, ive been hopping on whatever champ bandwagon seemed the most crowded at the time - and figured out what im worst at in terms of who my champ should be to help balance it - early game. Granted, everyone's bad to some degree early game simply due to lack of items and ults and whatnot, but i tend to overextend or not be aggressive enough.

Usually, assuming the lane isn't going well or i get ganked, it's for one of three reasons:
1) I get a foe down to low health and try to finish as they retreat into turret range, i try to make the last few hits and duck back to safety, but fail.
2) I get a foe into the red in health, only to have another foe leap from the underbrush (most recent was fighting Nasus and Pantheon jumped from nowhere)
3) I realize my range isn't enough and stay back when they approach, but they just feed on the minions until they can blaze through mine and then me.

Funny thing - going into the game, if asked if chasing into turret range for a kill is smart, id say no, survival > kills, but that fact escapes me when i actually have a chance at a clean kill and survival if i can dash in and do the damage before the turret takes me down.

Anyway, back to the issue - I'm not dealing sufficient damage to them - they keep running out of range, which is an obvious response you can't stop, but what if there was damage they couldn't stop even once in the fog again? The thin line is my issue - either too much health and they stick around to harass, or too little and they wise up and flee early to turret - I need a hero with DoT abilities - a few come to mind - Gangplank, Teemo, Brand, and Cass, but im not sure which is best suited to DoTs specifically as opposed to just having them - judging by Core's comment, Cass is, but I'll stick with GP while he's still free to see if i like the whole "run in, stick a DoT, run out, repeat" cycle.

Sion is the easiest champ, it really doesn't matter. No matter what champ is being dogged on, they're QQ'ING because they suck so bad they can't shut them down. Yi? Lol, I main that little eight-eyed *****, if you can't shut me down, you just have a poorly coordinated team, and you simply suck or didn't do your best. I'm one of the best yi's I've ever seen, and still, with slight effort I've been shutdown completely, wanted to break my monitor because I simply couldn't do anything. So instead of calling him easy, why don't you step up your game and kick the little fly's ass? Tryndamere, I've always hated this champ, he is so ****ing op, right? Not anymore, I don't know what patch it was but he is not the ad carry he used to be, with a good team and SKILLED LoL players, tryndamere is just like any other champion. Gangplank is not easy, morgana is not easy, warwick is easy, udyr is not easy against people who play LoL seriously, actually no champion is easy against skilled players. Besides one, SION, if you feed him at all, and I hear the commentator say he is unstoppable. I don't think twice about it, I type GG, and try my hardest. He really is, unstoppable.

Rumble.

For Akali specifically;

Apply your mark with Q, wait for your Q to refresh, initiate (post-6 with your ult, of course); and make sure you auto attack to proc your mark, immediately do it again.

You can also do this little trick from inside your brush if you KNOW you have to fight the guy on top of you.

I think renekton isn't too hard to play.