Personally I have only GDAX set up to buy LTC/ETH/BTC and move some to Binance for ALT trades.
Extremely happy with Binance, looking for another ALT site to store liquid trading pairs.
I can't get on Bittrex and that's looking to be a good thing. Not sure they are in for long haul.
And I checked an Exchange review site but sadly not one Exchange earned 4-stars.
Robinhood is launching Bitcoin/Ethereum trading with no fees next month. I'm moving some of my GDAX volume there to spread around the third party risk, and also because of GDAX's performance/downtime issues. Robinhood is my go-to for for stocks/fund trading, so it's awesome to see them entering the space. Great interface and good management. It's rumored that they'll be adding more coins as well.
Binance and Bittrex are your best bets as a USA resident. I also love Cryptopia, but not for liquid trading pairs.
Rather, it's good for buying cheap micro cap coins and speculating on them being added to larger exchanges. Sometimes, the payoff is huge.
All of the exchanges have their drawbacks....... shitty support, downtime, you name it. And every one of them will also have people claiming to have been scammed. Caveat emptor. I would say don't trust any altcoin exchange with more money than you are prepared to lose.