I grew up with PC, so it's what I'm used to. DOS gaming was where I was raised, and it grew from there. Building my first PC is one of my proudest achievements. (I haven't achieved much.)
I feel Mouse and Keyboard are much more versatile and precise for 3D games, especially shooters. Some games, I still hugely prefer a controller, like with Dynasty Warriors. Thankfully, I have that option.
You have literally thousands of games available in some degree on PC, and that's before you add emulation into the equation. IBM PCs are been around since the early 80s, and the flow hasn't stopped since. Also, PC seems to be much more welcoming of small indie devs than console markets, so it's easier to find fresh stuff.
Mods. They can make an old game fresh and new again. Doom has aged OK considered it's over 20 years old, but throw Brutal Doom into the mix, and it's brand new all over again. I pine for people who play Bethesda games on consoles, as they miss out on the glorious modding community, as well as fan bug fixes and balance patches.
Free games. Not even torrents, freeware stuff. Legitimately free, not allegedly free like most mobile games. The original Spelunky, for instance, is free and open source.
Customization. Pay for what you need. I bought an (at the time) pretty solid GPU because I play mostly action games and didn't need tons of CPU power. It's becoming a bit long in the tooth now, but an upgrade is only about $120, compared to a brand new console, and I don't lose anything.
And finally.