I've never been more impressed than when I discovered Linux. It's a pretty classical choice but I can't say another. It's my favorite because for every need you have, you get a solution to make it. Right now, I'm learning how xcb works to make a tool for DE like Rofi.

Most of all, Linux philosophy implies that the most popular (and almost always best) tools used on Linux are all open source. So now, I can learn xcb just by looking at the codes of other DE, I'm really in love with Linux