i want to get a marksman who should i buy?

I'd go with Graves, but then again I hate playing as Kindred.

...Neither are actual completely Marksmen, though I'd say it depends on your playstyle. Graves is bursty, Kindred is... well... not bursty? It's Kindred.

graves is kinda of a melee fighterish marksman, his full q deals a freaking huge ton of pun of damage his smoke bomb is great for 1vs2 situations and teamfights

kindred is more exciting in a way that you'll want to hunt everyone on the enemy team (if you do well, if you do bad hunt the weak link), her ult doesnt deal damage, but it can save from bursty enemies (rengar, zed, talon, kindred's ult allows you to be able to 1vs1 them), she has a really great E (the 3rd attack will most likely kills fleeing enemies with low health) and her w is fun plus it restores your health if you keep moving

Ezreal

Step 1) Buy zed Step 2) buy infinity edge, phantom dancer Step 3) ...? Step 4) profit

Kindred's not really meant for the ADC role due to her short range, but then again she was played as ADC by Origin =P.