I have used Coinfloor quite a bit and have had no problems.

Be aware that they might ask you to show evidence of the source of funds you send there, eg. if you sell a lot of Bitcoin they might ask you to prove where the Bitcoin came from. In my case, I was able to show the receipts from when I bought GPUs for mining back in 2011 and they were happy with that.

Their OTC market is (despite the wording on their site) available to individuals as well as institutions, should you want to trade significant volumes.

This thread probably belongs somewhere else!