Coinbase charges high fees as I'm sure you have noticed. Gemini's ACH transfer only permits deposits of $500 a day unless you wire transfer which can be a hassle. I prefer gdax because you can deposit funds of up to $10,000. The catch being it usually takes about four business days for the money to show up. They allow USD/BTC, ETH, LTC. ETH/BTC, USD, EUR, and LTC/USD, BTC, EUR trading pairs.

If you have anymore questions about exchanges and purchasing let me know : )