If you stay below 20Mb synchronous (i.e. 20/20) then a combined unit like the Tenda is fine.
As soon as you're thinking 50/50 or even 100/100 then you need to think about what processing power the unit has.
If you see yourself upgrading to that kind of bandwidth in the long term, then the better long term investment would be the ubiquiti devices.
You will be thinking in terms of 50/50 and 100/100 with multiple devices linking to the Wifi, streaming netflix and browsing or gaming at the same time.
If you like a DIY, then a small server running pfsense will also work 100%. I had one running for a while and it was beautiful.
The latest updates to the uniquiti routers has a very nice graphical breakdown of what each device is doing and how much bandwidth it's using. Something that I like a lot