cex.io is quite a decent exchange that I personally use.
Here's a link to register, referral, if you don't mind
https://cex.io/r/0/up105387737/0/
Here's a link to register, referral, if you don't mind
https://cex.io/r/0/up105387737/0/
poloniex / bittrex / bitfinex
I recommend this to several global websites
However, these sites cannot be purchased using legal tender.