PC Engines APU-2 rocks; what’s next? (Hardware suggestions, ideally x86?)

Hi all. I'd like to first report my experiences, and second ask for some wisdom.

I've got a PC Engines APU-2 4GB w/ 3x Gigabit NIC which I bought a RouterOS x86 license for.

It ran pfSense and that was fine. Then I upgraded to opnSense, and that was also fine..but we upgraded to 750/750mbit, and it couldn't keep up with the bandwidth.

Then I bought a Hex Refresh and it couldn't keep up without fasttracking everything. I loved Winbox (Linux user, and it works great; the MAC-based admin interface is ingenious when IPs are down, multi-window admin is SO nice, a CLI for when I want it, etc etc, cannot express how much I love it!)

Then out of desperation I tried RouterOS on my APU-2, by kind of just figuring my way through getting it on there (was pretty easy; USB and Serial, didn't need a guide) and it's been a dream.

I recently added fiber as a second WAN (so, WAN1 750/750 and WAN2 1000/1000) and I have railed on both at once, and gotten a sum total thusfar of fully saturating a gigabit split across two WANs. It also, of course, handles a gigabit over one WAN — and this is without fastpath. I'm using queue trees with various pcq/cake/red configurations, complex firewall tagging rules, ein, six-figure address blocklists imported from AbuseIPDB, IPv6, bridges and VLANs ….

It's easily configurable for "full cone NAT" aka "open NAT" (yeah it's an old term but gamers get it) and everything else necessary. DHCP and DNS you can fully own, or hand off to another device/service. Absolutely everything I want in a router, and a team who listens to people who use it. (I even noticed a DHCP Routes bug in Winbox which was addressed by the next patch before I could report it, lol.)

Genuinely, if you need a gigabit router which doesn't break a sweat doing it, dust off the APU-2 or grab your buddy's. They were popular for a long time, but PC Engines has stopped making them, and they're difficult to find places like EBay. If you're considering your next router, very seriously look into RouterOS devices, or RouterOS on your existing device instead of the existing OS — it genuinely can outperform pfSense/opnSense on the exact same hardware, in cases like mine.

Which leads me to my question; What's next?

My fiber could go up to 3gb. My router can't, lol. What's a multi-gigabit capable router which can actually handle a full workload, but won't break the bank- I own it, I put my OS of choice on it, and it does its thing for the next decade, even if that's with another platform. Anyone feel passionate about their hardware of choice?

The APU-2 was $225 when I bought it years back, and holds up to full gigabit today; I'd consider it the gold standard of its generation. What's this generation's gold standard DIY device?

Any experience with RouterOS on something like the ZimaBlade 7700? The Zima store sells a few multi-gigabit cards. Can it keep up at all? Maybe a specific particularly cheap old office workstation SFF PC with an extra NIC? An overlooked gem like the APU2? I welcome contributing opinions.