I keep hearing people are using Binance -- but I have been using HitBTC... I like the interface, market depth, charts, annoying people posting on at chatbox 24/7....
If you already own some cryptos (BTC, LTC, ETH, whatever) then you can transfer from your wallet to HitBTC. I (Canadian) signed up for QuadrigaCx and bought coin there & transferred to HitBTC... You could do that with Coinbase or anywhere. Only thing is, different exchanges have different prices, so depending on the price difference, you'll incur a bit of a loss transferring (but then you'll make that up when you transfer back out, so long as you're smart about it). This is where I am at with Quadriga, and I imagine it's the same with several others.