from a professional standpoint, linux is the only one. (webdev here.)
on the other side, from a normal user standpoint, I really like using OSX.
Linux for web servers or vps or pretty much any bitcoin applications is the way to go. I had to use it and learn it for a couple projects but I had to use the SSH command line to access it and it was very very hard. I just have to figure out how to use remote desktop and I will be able to do this much quicker. I wish someone made bitcoind hosted servers where there is no hassle of setting up your server and configuring it, it is just ready to go out of the box.