Router abilities

Hi,

i own 3 RT68 Witz Aimesh. No i am thinking about to replace the main Router with a AC86u. The other will not gain the features from the 86u, right? Will it better to replace the main and the router where the most devices will connect to?
Replacing all three devices is to expencive at the moment.
Does it make sense to replace the devices?

Kind regards