I have a two and a half year old, so my take on his behalf is a true understanding of toddler dexterity and what their relative level of ‘success’ in play might be. He can get frustrated quickly if things don’t go together or need perfect alignment - even Duplo (big Lego) requires that planes be parallel and correct assembly doesn’t come with overt feedback. I like multi-use toys that inspire imagination, are durable, and without too much of a designer’s ‘hand’ involved. Give a kid a silicone spatula and you are set for an hour.