Should I upgrade to a wifi 6 router or just get a new wifi 5 router?

I have had a Netgear Nighthawk R7000 Smart WiFi Router (AC1900) for the past five years and it's been great, but it's starting to show its age. I've "fixed" it many times but I'm ready to get a new router. My question is, should I get a high end ac router or should I just get a fancy new wifi 6 (ax) router? I know I need Wifi 6 compatible devices to get the full benefit, but if I plan on keeping this for another five years, should I just upgrade now?

My household has way too many devices from phones, tablets, laptops, tvs, and smart home equipment. All together, there are probably 20 devices connected simultaneously and around 70 connected devices in total. I work from home and download/upload a lot. I'm guessing more than most, so speed and reliability are big factors (as I'm sure it is for most people). My home is about 2000 sqft but I may be moving to a bigger home in the near future. If that does happen, does it make sense to get a mesh system that I can add too?

I've been looking into the Netgear Nighthawk AX8 AX6000, Ubiquiti AmpliFi Alien, Netgear Orbi Mesh Router, and the Asus RT-AX88U. Any thoughts on these?

Sum up/TLDR:

1. Should I upgrade my router to wifi 6 (ax) or get a newer wifi 5 (ac)?

2. Which router is recommended for 20+ devices connected simultaneously and won't throttle speeds?

3. Would a mesh system help with the issues I have with the number of devices and throttled speeds?

4. I have all four of my LAN ports being used and could use another two. Does it make sense to get a router with more LAN ports, like a TP-Link Archer AX6000?

5. What router would you pick in my situation?

There is a lot of info out there and it can be hard to filter out the BS so any advice or recommendations would be greatly appreciated!