Wow realllllly tough question lol. Its a combo of a few things for me:
1. I only have bps right now. I love their "paintjobs" as slim said. Theyre awesome!
2. It only takes a small amount of space to keep quite a few of them compared to other pets.
3. I love the genetics of them. My favorite chapter of biology in highschool was genetics. I was a loser and did punnet squares for fun lol. The genetics of bps takes that love to a whole new level for me. I cant wait to try my hand at breeding next year!
4. The last reason i have is the WOW factor you get from peoples reactions. I dont go around bragging about them but if it comes up in conversation ill mention i have snakes. The look on peoples faces is priceless lol. Their jaws drop and they go, "You keep PYTHONS? ohhhh woowww". Acting like i have a 30ft snake in my house lmao... Yea ok... This is not why i keep them, but its a cool bonus that comes along with keeping them