rax18 or rax40?

I recently purchased rax18 wifi 6, a huge upgrade from an old wifi 4 router, for an 1900 sq ft house with a 200 mbps download speed from Cox. It is only my wife and I with 3 laptops, 3 ipads and 2 cells. 2 cells and 1 ipad are in wifi 6, everything else is on wifi 5. With both of us working from home now and are on video calls most of the day, I saw an immediate increase at the far end of the house from the router (but needed an extender) up to around 50 mbps on the laptops, but I am wondering if the rax40 would give me better speed and coverage? Any suggestions would be greatly appreciated...there is only a $60 difference.