Gemini is my preffered exchange for these reasons: 1) Instant ACH Deposit. You can deposit from a bank, and instantly trade with those coins. Up to $500 a day 2) Lower Fees. No deposit fee, trading fee only .25% and no withdrawal fee.
Things I would like to see improved: 1) Allow more ach deposits daily, maybe through better verification, up to 5k a day, 25k a month.
2)Add more coins
3)Implement SegWit. If you can implement segwit it shows you are dedicated to improving BTC.
4 ) Support weekly/monthly buys. This is a simple concept, and Coinbase has a lock on it in the USA.