Krastorio 2 is the recommended overhaul mod after a vanilla playthrough. It makes the game somewhat harder than vanilla, although I don't really know what it contains as I never played through it.

Industrial Revolution 3 is another good choice.

Or you can jump off the deep end like me and start a Angels+Bobs map, but this is quite difficult dealing with many byproducts and thousands of recipies. Also, you don't need many trains to beat it, I beat the modpack with 3 train lines, but if you want to scale up trains would be useful.