Theropods are always good choices ! I've mentioned a Giganotosaurus to Jorge several times..he agrees there should be one..same with a Ceratosaurus ( horned theropod ).
How about a Giga pack hunting down an Argentinosaurus ? ;D
I'd love an Allosaurus maquette ! He got a VS Dio but like Rex was the King and got his own maquette, Allosaurus is the Prince and needs his own as well ! ;D
I want some marine reptile..Liopluerodon, Kronosaurus, some Pliosaur would really nice..though I think if I had a preference it would be for a Tylosaurus and/or a Elasmosaur in a VS Dio as in Journey to the Center of the Earth.
To round out my list of demands ( aside from those I already mentioned ) :
Ankylosaur of some sort..preferably club-tailed..not a Nodosaur.
Brachiosaurus
Diplodocus
Dilophosaurus
A Pachy is good..Dracorex would be fine and it's popular.
Flying Pterosaur
Another ceratopsian of some sort.
A hadrosaur maquette ! Maybe Lambeosaurus or Orlorotitan..heck even a Maiasaura with nest and hatchlings.
Dromeosaur ( raptor ) maquette.