I use a couple of Archer C6 v3.2 routers. They’re good for the price and work well with OpenWRT except for a crash/reboot loop which seems to be caused by HW accelerated NAT (See Archer C6 on 22.03.2 crashes every ~3 days).
The dual core is easily up to WiFi routing but as you have guessed routing gigabit SQM would need a much more powerful solution
I really wouldn’t worry about gigabit ports. Anything with 10G ports is going to be very expensive, and if/when you need them then a proper managed switch is probably in order. Unless you really think you already have multiple devices regularly saturating their 1G links and being constrained by a 1G bottleneck elsewhere then I wouldn’t bother.
The main future proofing is in the cabling that you use. Decent CAT6 is worth it now, as you don’t want to rip up your house to get 10G if you need it in 5-10 years. The rest of the hardware will be cheap and easy to replace in future.