If you're connected to a Huawei FTTC cabinet (see here) then i would go for the Netgear D6400 as that has the same broadcom chipset and also it was one of the first VDSL2 modem routers to be released so should have stable firmware. However for 93 quid Amazon are the selling the superior TP Link VR900, albeit a nearly new model. This also uses a broadcom VDSL2 chipset but its wifi performance is significantly better than the 2 routers you mentioned.
Or 105 quid from ebay
I'm pretty sure we're connected to a Huawei cabinet even though I can't actually find my cabinet
The BT wholesale checker says I'm connected to Cabinet 18 with a minimum of 79.8Mbps and a maximum of 80Mbps so it must be pretty near by! I've attached some pictures of local cabinets from around my street and maybe you can help me identify them as they aren't numbered!
And out of interest, from the link you provided regarding the cabinet type, what does it mean when it says:
"The FTTC cabinet will usually be located no more than 50m from the green PCP cabinet as per recommended guide lines. In exceptional circumstances the absolute maximum is 100m"
What's the difference between a PCP cabinet and an FTTC cabinet?
So this cabinet is located about 10M from our house, just round the corner:
Then about 50M away on a different road there is this cabinet:
At the end of our road, about 80M away, there is this group of run-down cabinets:
And finally, about 100M away, over an a different road is this BT cabinet, with no number and no grills