If you want the most configurability, run your routing on a PC or two. I've got a rediculous setup with two redundant routers and all that. The nice thing is when it's working properly, I can reboot either router for software updates with very little noticable impact. The not nice thing is it took a lot of work, and it doesn't always work that way.

Then deal with the APs separately; you should be able to setup a mesh system without having it do routing and NAT; I only have exposure to ASUS's aiMesh on underpowered hardware and I went back to separating the APs, but mesh makes a lot of people happy, so you do you.