CAT 6A seems fine enough for future proofing, CAT 8 seems overkill, at that point might as well consider fiber as well

Mikrotik isnt really known for their wireless stuff, so I woulnd't go for them for that, but their routers are rock solid

for other wireless providers, consider Ruckus Networks or Aruba Networks
Both are not cheap at all though (but still cheaper than cisco)
Or Ubiquiti can be considered but their software is rough around the edges