garen is pretty good, but you must find champs that suit your play style. riot has "recommended" champs, but they're pretty bad (ashe is prbly the worst adc in the game, not counting urgotif you enjoy playing a tanky melee top, give olaf a shot.

this is a little off the OP
ashe does not have the easiest cs (that would be draven and trist and sivir both have easier cs then ashe) she has zero escapes and does the least damage throughout the game. her short range frostshot has a really short stun. her harreses (volley) has a really short range and she has no steroid

Frost Shot is a permaslow (not stun) until she runs out of mana, Volley and Giant Arrow (which is a global skillshot) both enable escapes, and Hawkshot gives her extra gold per kill, making her CS worth more than, I think, every other ADC. (Including Twisted Fate if that's your thing.) Though, point taken about the lack of steroid. (Her passive allows for nice poke, but it hardly qualifies as a steroid in teamfights.)

Granted, I prefer other ADCs, so that does say something.

Ashe has great damage output if you build correctly. Her ability to cs is amazing, her harass from lvl1 to 4 or so is fantastic, and she can kite like a boss.

All that being said, she has to be played with a team that can keep people from diving her. As riot now makes every champ so that they can dive squishies, her usefulness has fallen off quite a bit. But put her with a Jarvan top or jungle and an ali support, and she will excel. Remeber her ult acts as an aoe slow as well and if you are good enough to launch it as your team starts to engage it can devastate the enemies ability to counter initiate.

All that being said, Garen is a boss. He might not have the fancy kits that a lot of these new champs have but he can **** on them in lane, and his aoe and silence work well in team fights. I do recommend a jungle or support with a hard engage when you have a garen though.

I recommend Amumu, there's no wrong way to play him.
Turn on your W, Q, Mash E, profit.
Ulting the whole enemy team could you get your team the victory.
Plus, he's great to learn to jungle with.
Try him out.

I heard the same thing when i started playing garen, though i hear since season 3 he's gotten way better. so maybe you are reading old info.

also. i'm finding very late that one of the most valuable things you can do is learn as much as you can about as many champs as possible. just play them all.

also. just play the champs you enjoy and f the haters.

When I first started playing, I had no idea what I wanted to play, so I just played every free week champion every week. I began to find patterns in the champions I liked (Jax and Vayne were the first two I really liked) that they were all highly mobile lategame champions so I searched some other similar champs and fell in love with champions that were great at closing distances like Ahri and Riven, and other lategame champs like Hecarim and Kogmaw.
I'd also recommend going onto the LoLWiki and searching up who designed your favorite champions, in your case, Garen was designed by Geeves who also designed champions like Trundle (Free for today), Kennen, and Xin Zhao, so I'd say play those since they were designed by the same person.