Firstly, do you really need the a6300? A better bang for buck would be to get the predecessor a6000, which cost relatively lower. The only extra feature is 4K video and better auto focus and viewfinder.
I haven tried the a6300 but I think the a6000 AF is already very fast. Unless you really need it to track moving objects e.g. Shooting sports you probably wouldn't get much out of the faster AF.
As for lens... Which lens are you comparing to? The kit lens is good for a start though it certainly wouldn't be as sharp if you were to compare it to prime lenses at the respective major focal length 16mm..35mm.. 50mm..
But I think it's good to have the flexibility to zoom for a start and with the discounted price with the body, it's all good. You can add in better primes in the future
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