Frankly speaking until now I have used bitfinex and hitbtc both of them work on USDT model and frankly speaking I have found them to be quite good with easy deposits and withdrawals for USDT and other cryptos too. You can share if you have faced some problem so everyone else could be a bit careful in future.
No problems so far but this lack of serious audit about backed USDT is really scary. Looks like bomb which is going to explode and make total crash of cryptos.
You made me check the tweets out there that has "#DontGetTethered" since I'm not putting that much time on tweeter.
Reading the pinned tweet on that "bitfinexed" account interesting on how bitfinex is doing crazy with tether.
Still keep an eye on your trades and I had no idea if they are just trolling or what.