Sounds like you are probably syncing at the max rate on an 80/20 plan (I guess you are quoting real speed tests results rather than line). So nothing really to be gained by a better modem in terms of connection speed or proper stats monitoring.
I guess given people don't complain about gaming the 80/20 connection is solving the QoS problem by fat pipe, no one runs torrent clients set up to max out the connection both ways or uploads large backups and the like on a regular basis.
So based on that and your already in place wifi solution, pretty much any decently regarded modem-router combined box will probably work fine. As others have said the zyxel routers are highly regarded here (and I agree, though only use them as modems). 1312, 8324/8924 will all probably serve you well, the 3925 as well, but its slightly harder to get stats out of (if you even want that). All can generally be purchased best by watching ebay for a while for auctions rather than the stupid buy it now prices that seem to be normal. If you are spending more than £40-50 its probably too much (unless you
really want it
now).
However if you want something more, either just to tinker with or because you think maybe there are performance issues with your usage that you currently don't even notice due to not having had anything better before - maybe some people experience lag sometimes and think its just the "internet" when really its contention for bandwidth affecting their gaming or voip, then there are more options.
Full disclosure, I really like the openwrt/lede project and run their open source firmware on several devices. I believe it has probably the best QoS implementation of any router firmware currently available, its called SQM you can google it. As best I can ascertain its the most advanced way of managing your up and downstream in a fluid way to ensure decently low latency even with users saturating your connection without having the pain of having to specify ports or protocols that have priority. It takes very little setup and just works.
So if you like the sound of that (and an open source firmware with the latest linux kernel) - to shape an 80/20 connection (and still have overhead for lots of connections for torrents etc) requires a little more grunt that the cheapest routers you can find that support openwrt/lede. If I were in the market for a compatible router for that connection I'd be looking at the linksys WRT AC series. The cheapest one (circa £100 new, £60-70 used) the WRT1200AC has a 1300mhz dual core ARM CPU, which should be plenty, and they go up to 1866mhz (more money). In comparison, the zyxels use 400mhz MIPS cores, significantly slower.
This setup will require a separate modem, so one of the zyxels mentioned previously. Plus the added hassle of flashing/configuring.
My 2 pence.
Edit: typos