So I have used a lot of different distributions in my day, anything from Damn Small Linux (DSL) to all the mainstream ones. As for what my Favorite one is I don't have an exact favorite. They all work very well.
I will say that I have an Ubuntu server running this is for ease of access because I am kinda lazy. The only way I connect is with Terminal, which isn't that hard to use once you know a few commands.
I have Fedora running on my laptop most of the time. I like Fedora because of the community it has. There are a lot of people that will help you even when the problem is minor, and it has been asked a thousand times.
If I had to choose a true favorite I would say it is two fold. I really like Gentoo, and Slackware. This is because I have to do pretty much everything for myself in building the OS and choosing what programs I want to run. Now I would appreciate it if you don't go and call me a fan boy but I should expect it.