For your first purchase spend 20 bucks on Coinbase and see how it works out. Their UX is miles apart most others and its good for seing how buying bitcoin actually works. The fees are up to 16x times higher than some of the others (4% compared to 0.25%) so don't spend a lot here.
For USD / fiat -> crypto (Usually the larger coins only) in descending order:
Kraken
Bitfinex
GDAX
Localbitcoin is also very decent. A p2p platform.
Personal favorite is Kraken. If in Europe a bank transfer takes about 1 working day and then you can trade with 0.16% fees.
crypto <-> crypto:
Binance
Bittrex
Poloniex
Small caps:
Tradeogre
For USD / fiat -> crypto (Usually the larger coins only) in descending order:
Kraken
Bitfinex
GDAX
Localbitcoin is also very decent. A p2p platform.
Personal favorite is Kraken. If in Europe a bank transfer takes about 1 working day and then you can trade with 0.16% fees.
crypto <-> crypto:
Binance
Bittrex
Poloniex
Small caps:
Tradeogre