Top ten routers currently in use?

I agree with that, any kind of popularity contest will inevitably be skewed by older devices - which aren't necessarily a good recommendation to buy today.

E.g. for a long time (and even until 1-2 years ago), the tl-wr841nd (ar71xx, 4 MB flash and 32 MB RAM, so basically in the same boat as your wnr2000v4) was very common and even recommended by many (despite the strongly repeated 4/32 warning ("but it worked fine in 15.05…")), because it was cheap (this mattered especially for larger deployments, like e.g. freifunk, who tend to buy devices in larger quantities; yes, they are now facing a pretty serious problem as well, even worse, because many of their participants have bought these below-spec devices until very recently or even just now…). For obvious reasons these devices with 4 MB flash or 32 MB devices can't be recommended anymore, even if the existing install base might be rather large.

Yes, it does matter which SOCs and devices are popular, but that list also needs to be cross checked against devices that are available for sale today - and whose hardware is good enough for the expected lifespan of that device and your actual needs in terms of performance and/ or budget.

Personally I'd condense the recommended set of readily available devices to (medium- to highend, non-exhaustive):

  • ipq40xx
    • AVM Fritz!Box 4040
    • ZyXEL NBG6617
  • ipq8065
    • Netgear Nighthawk r7800
    • ZyXEL NBG6817
      • or the older ipq8064 generation
        • Linksys EA8500
        • Netgear Nighthawk r7500v2
        • TP-Link Archer c2600
  • mvebu
    • Linksys WRT1200ACM
    • Linksys WRT1900AC/ WRT1900ACS
    • Linksys WRT3200ACM/ Linksys WRT32x
  • x86_64
    • there are quite a few low-power (<6-10 watts idle) devices with multiple ethernet cards on the market, mostly directly from asia; wlan is often more difficult here, meaning you usually need to outsource it to a dedicated AP (e.g. from the list above).

Both mvebu and x86_64 can be used for 1 GBit/s WAN speeds.

Additionally there are also cheaper options available:

  • mt7621
    • Xiaomi Mi Router 3g (mir3g)
    • ZBT WE1326
    • ZBT WG3526
  • ar71xx/ ath79
    • TP-Link Archer c7 (hardware revisions v2 and above)
    • … (for supported devices, as long as it comes with >8 MB flash and >64 MB RAM)
  • lantiq
    • BT Home Hub 5 Type A
    • … (for supported devices, as long as it comes with >8 MB flash and >64 MB RAM and good wlan (QCA/ Atheros))

Obviously there are many well supported devices matching or exceeding the minimum systems requirements beyond these - including different archs/ SOCs.

While you are right that these 16 MB RAM devices aren't fit for actual usage anymore, you'd be surprised how often support for these is still requested (or even demanded). Yes, even today, it's not uncommon to see support requests for these once or twice a day.