Magna tiles - or a version of these.
Definitely number one toy in our house, he plays with them every day at home and at pre school. I really wish if got them earlier for my older daughter, she is nearly 8 and often still dives in. We have parts from three different sets, and all equally fun - the kit I've got for Xmas/ his birthday ( these are close together) has more wheels as he continues to be car mad..
I recommend Richard scarry books, very funny, can read over and over. Also little red train has longevity, eldest uses it as spotting book.
Spider-Man spotting book
Scratch art book
And crocodile dentist game and I'm looking for other family games he can join in with, possibly cooperative type
I usually ask grandparents for a couple of pricier clothes things- eg frugi hoodie, Boden something. We normally have loads of handmedowns but the things that get a lot of wear it's nice to have a couple of new things.
Possibly jigsaws, he loves jigsaws.
Recently got his own pencil case and purse, thrilled with these.
Maybe pants socks wooly hat in stocking