Well, i dont think theres much room for improvements here.
Between ERL and ER-PRO, both will do the job. I dont think you need the extra ports from the ER-PRO, but if you want to apply some QOS rules in the future, the PRO is a stronger product.
Since you are going with Unifi Switch and UAPS, i would suggest an Unifi Pro 4 as a router for you.
