I use CEX.io. Please do not buy bitcoin/eth from the buy/sell page. They sell with a markup because they're selling the currency in bulk. The markup is significant, the trading price could be at $290 and you'd be paying $310. Buy eth and bitcoin from the trade page. Just put a limit or market order for the amount of currency you want, or a fraction of it, and you'll quickly get the same amount of coins but at a fair price.

As for good exchanges, CEX.io is great. Nice trading experience and UI, commission is typical, it's an established an mature company relative to other exchanges. It's also nice to be able to deposit and withdraw fiat using credit/debit cards. Only problem is support can be a bit slow sometimes.

I heard Gemini is probably the best exchange out there right now. Secure and fast support. I'm trying to get into Gemini too but need to wait till I get back into the country from vacation.

Like CEX.io, you can deposit and withdraw fiat using credit/debit cards in Coinbase/GDAX. HOWEVER, people recently has been having significant issues with the service. Slow support and the website crashing at crucial trading times (low prices) has been a big pain for many (I think almost 4 crashes at low prices in the past month?). That said, Coinbase is prob the easiest way to get into crypto trading.