League of Legends (LoL) Question: which one is better?

Graves is a safe pick this meta nowadays. Jinx is the best hypercarry so far. But I think Graves is just a better pick cause he has what all you need for an ADC. Tanky because of his passive, best burst from adc's from his Buckshot and Ulti, smokescreen is decent for zoning and slows, and his gap closer/escape is unique as well, cause you everytime you hit a unit, its cooldown decreases by 1sec.

It depends on your skill level, Graves is easier to handle due to his relative lack of tricky skillshots and inherently forgiving tankiness for an ADC. However, Jinx's Zap! and Flame Chompers! outstrips Grave's Smoke Screen in CC, so Jinx is also a much better pick if you're unsure about your support and sure in yourself. Graves has a dash on a short cooldown in combat ( Quickdraw), and is better in chases, as well as the dash being a forgiving answer to bad positioning. Basically, your choice depends on how good you are with an ADC, as well as if you have a good duo queue support.

They are both fine picks. Graves is slightly safer for team fighting fire to his inherent tankiness through his True Grit. Jinx snowballs better though and can take / siege towers better

Well, as said above, Jinx is already a pretty good pick. Graves is also pretty strong as of now, since he can deal pretty well with assassins. But given that in Bronze/Silver the dominant meta isn't THAT important, I would recommend you Caitlyn. She's a good all around adc, with the longest range and pretty easy to use. Just read a couple of guides and poke behind your melee minions.