After reading the posts here ages ago about replacing the Plusnet supplied router I installed a Asus RT-N66U router.
It's been rock solid, but of late neighbours (not next door neighbours either) have been showing a stronger Wifi signal (BT) than mine on both 2.4 and 5 even though mine is just across the other side of the room.
After reading the reviews and looking at prices I've gone for a Asus RT-AC68U. I couldn't justify the £300 for the 88U.
My Wifi is now stronger than theirs - I'm the boss in my own house again.
One thing I did find odd on first install is that the 2.4 Auto setting chose channel 10 !!! Not only a weird channel to choose but also crossed the most populated spectrum area round me. I can see just under 30 other 2.4 subscribers near me in Wifi Analyser but only 3 on 5Ghz. The 5G Auto selector also went on the same channel as one of them.
I'm of the distinct impression that the router auto channel select is pants (technical term).
It shouldn't really matter much which wireless signal is stronger than another. Wireless works by each device checking if the channel is clear before transmitting, not by trying to blast a stronger signal over another signal. All that should matter is if it has sufficient signal strength to get the required amount of bandwidth to where you need it.