Depends.
What are your ISP speeds? Are they limiting you on any one device now?
What are your current network experiences? Are you seeing a decline in network responsiveness when all your devices are connected and in use?
What is your current WiFi coverage? Is any client device and or activity on that device being limited or reduced in any way now?
While the new routers will give better performance than any old model will (no matter how great it was), that doesn't mean you need to jump now.
In the Asus arena, the RT-AC86U was comparable to the R7800 if I remember correctly so far back. Today, the RT-AX68U, RT-AX86U, and GT-AX6000 all surpass it easily. And for me, that is very noticeable and appreciated.
Not so much for just raw download speeds. But for what those higher download speeds infer too; lower latency (and that lower latency is inversely proportional to the increase in download speeds, ime).
For reference, here is what the entry-level RT-AX68U performed vs the past 'king' RT-AC86U.
Report - 2x RT-AX68U upgrade over 2x RT-AC86U in wireless backhaul mode
And the RT-AX86U is faster still. And, the most balanced (hardware) Asus router, the GT-AX6000, being about 20% faster throughput too, than the RT-AX86U.
Hope this information helps.