STLE is the most popular with guests at the house. People gravitate to it more than any other game in my collection. XM is a good pin. There's a few bugs, but I've gotten over it...mostly. I recommend the XMLE over the pro. I like the additional movement on the playfield and the added difficulty it brings. It makes it more interesting for me.
Both games offer choices on how the game will proceed, which is nice. You can choose your modes to a large extent so that you don't have to play the game the same way each time.