kalista or draven?

You can't ask community whom to main, it's all about what fits your playstyle. But I would prefer Draavenn. :3

Kalista is all around a better adc. Draven is very difficult to get the hang of with keeping his axes up and using his w and e efficiently; his team fighting and positioning are also incredibly difficult to master.

depends on your playstyle.

both have a similarity in the interaction between they attacks and movement, draven has to catch his weapon after firing and kalista gains hyper-mobility with her attacks as she gets to jump each time you attack.

draven has an ult with "global" range (execute) kalista has a couple of abilities that require a support nearby.

draven attacks less often but deals tons of damage. kalista scales well with attack speed and has infinite kiting (due to her jumps)