Here are some of my 3 yr old son's favorite toys:
Bunch of crayons/washable markers and paper to draw on or coloring pages printed off the internet
Matchbox cars
Train set (with wooden rail like Thomas sets)
Sand box toys /playing in the sand
Playdoh
Stickers
Simple puzzles (Melissa and Doug wooden puzzles where the chunky pieces can also be used in pretend play) (my son moved on to more complicated puzzles now)
Balls (a big plastic ball to kick around in the yard)
Dinosaur toys
Pretend play:
-Dress up (especially hats)
-Cooking (pots, pans, spoons etc) He loved "cooking" and then serving the food to us when he was around 2 1/2
-Tools (toy hammer, wrench etc)
Recently he started to show interest in action figures.
I think all toys and games are developmental, in that they help them develop ;-)
Actually my son plays better with simple things around the house better than expensive toys, most of the time. He loved taking measuring cups and spoons from the kitchen and cooking with them, for example. Also, if he "finds" something himself, rather than me handing it to him, it is much better! So I sometimes strategically place a toy so he "finds" it ;-)
EDIT: For sensory issues, different textures and water and sand play would be great. At my son's preschool, they have a "sensory" table (a table which is like a shallow tub) where they put various things like sand, rice, dry pasta, beans, coffee beans etc mixed in with a bunch of different little toys or scoops. Also, playdoh or pudding/yogurt as toy, or balls with different spikes/textures would be good.
You can also ask the occupational therapist for recommendations.
You can google "sensory toys" or "sensory toys for toddlers" to find some ideas. Such as:
http://sensoryuniversity.com/?gclid=CKCwkbur-agCFU5qKgodk...
http://www.sensoryinterventions.com/