Been weighing up a similar dilemma and finally took the plunge on... an Asus RT-86U. I figured it’ll offer a significant improvement over our current BT SH2 and should give decent coverage. If additional coverage is needed will use gigabit backbone already in place and purchase another router.
BT actually supply some really good 802.11ac modem/router/access points. I doubt you’ll see much benefit in WLAN coverage by shifting to that ASUS. As for anything else, yes, you can probably find a few features on the ASUS that aren’t on the SH2 but for £150-ish I’d want so see a significant upgrade in features or speed.
A major part of the challenge with WLAN is getting folks to understand that 100% of all the marketing stuff you see and read is total BS. Almost all of these devices use the same internal chipsets (because there are only a couple of manufacturers) and when push comes to shove, this is a 2-way radio.
It’s VITAL to remember it’s a 2-way radio because even if you have a 4x4 monster access point with humongously sensitive antennae, if the thing you’re attaching to it with is a 1x1 Ring doorbell with a tiny antenna, the perceived range is going to be awful. And slow.
Most people don’t have any 4x4 wireless LAN clients. There’s a couple of Samsung flagship phones but by far the majority of phones and tablets are 2x2 WLAN on both the 2.4GHz and 4GHz bands. And they have tiny antennae and tiny amplifiers so they don’t go as far as your wireless access point can. So the end result is the perceived range of the access point is poor, when in fact it’s the wireless range on the client that’s poor. But everyone blames the access point. You don’t want massive range, you want great coverage. And that means shortening the distance from the client to the access point as much as possible by placing your access point as high up and centrally as possible. the landing ceiling is the perfect place in most homes.
UK builders tend to put the master phone socket by the front door. And maybe an extension to the corner of the lounge. Behind the TV usually. The worst places EVER. And pretty much everyone blames the router. Because BT’s routers are crap. Everyone knows that. Right? Wrong!