With the Troodon's introduction, we have the minimum usable size for dinosaurs, which opens up a lot of options for more small dinosaurs, especially small herbivores (the only representation at the moment being the three boneheads) since there are a bunch around Troodon's size and between Troodon and the Velociraptor, the largest small dinosaur. What small dinos would you like to see?
For comparisons using Troodon, here's the relative size of it in Evolution:
Bringing back the two OG littlesaurs Dryosaurus and Homalcephale is a big one, of course.
(Prenocephale used because couldn't find a good one of Homa and the theory that Homa is a juvenile Preno)
Oviraptor is another good choice, with its very distinctive head shape, crest, and beak.
A very good choice for a small ceratopsian is Psittacosaurus, with its distinct head shape and the tall row of bristles on its hips and tail. The image shows P. mongoliensis, but the species used could be P. lujiatunensis, one of the two larger species which were around 15% larger.
And not forgetting the classic Coelophysis.
For comparisons using Troodon, here's the relative size of it in Evolution:

Bringing back the two OG littlesaurs Dryosaurus and Homalcephale is a big one, of course.

(Prenocephale used because couldn't find a good one of Homa and the theory that Homa is a juvenile Preno)

Oviraptor is another good choice, with its very distinctive head shape, crest, and beak.

A very good choice for a small ceratopsian is Psittacosaurus, with its distinct head shape and the tall row of bristles on its hips and tail. The image shows P. mongoliensis, but the species used could be P. lujiatunensis, one of the two larger species which were around 15% larger.

And not forgetting the classic Coelophysis.
