I have owned quite a bit, but, I have trimmed down to just the Dark Knight line. I'll still include pieces I have owned in the past.
1. DX Joker (such a great figure, so nice I brought it in to work to show some friends, everything about it is top notch, including the packaging)
2. Batman, original suit (took me awhile to track one down last year. Was able to land one from a board member. Iconic figure in the Batman line. Sure to keep going up in price too, in my opinion.)
3. The Godfather (sold it, but, it's still a great piece)
4. Cannibal Jack Sparrow (again, sold it. But, great likeness and totally captures the character's quirkyness)
5. Bank Robber Joker (just because it's my favorite character, and love posing it the same way as the movie begins, with his back towards you awaiting for the car to pick him up)
Good luck on the collecting. There sure is a lot of really nice figures out there from Hot Toys, I also had the Iron Man mark 3 which was great as well, and always wanted to get the mark 1. But, that is when I decided to cut back on collecting.