Akali is more single-target burst, Kat isn't really that strong anymore unless you build tank kat and just sit in teamfights spamming w and eating cc. Neither really brings anything to the team per se.
I would say Corki is still viable, but he's probably not as strong as most other adc, so I would advise against just picking him up if you're unfamiliar with him. Draven is without doubt the strongest adc in terms of raw damage from early on, but you have to be really good at microing to catch those axes.
I think you should be fine with MF/Graves/Ashe, since they are all very strong, but fill slightly different roles, so you can adjust to your team comp.