World of Warcraft with over 11k hours. Guild wars 2 is probably 2nd with over 6k. The highest on Steam is Warframe with 2329.
For WoW and GW2, it's basically the same reason. I loved MMO games and the huge world you can explore. I found guilds in both that I vibed with, and still talk with some of those folks today.
For Warframe, the gameplay is top notch IMO. I didn't mind the grind (I was a MMO player, after all) and the selection of warframes and loadouts kept things from getting too stale. I mainly played with one of my friends I met through WoW, and we roped some friends into playing with us from time to time.
I still get the itch from time to time to get into a new MMO to try and relive the experiences I had from previous games, but those days are most likely behind me.
FFXIV is one of those games that I liked, but wished I could like more. I wasn't into progression raiding or crafting, so it was always a matter of time before my interest would fizzle out once the current MSQ was done.
Your character looks nice, btw.