@dee.jay - arguably the ZyXEL VMG1312-B10A or its more modern replacements and their higher end wireless modem-routers. ZyXEL have stopped selling the B10A, although new ones can still be found but they are starting to get ridiculously expensive as they are so highly sought after. I suspect that there are other models that are equally good in respect of the modem part (I hope so anyway), and there are now ones that have much better wireless. All of these have a high quality Broadcom chipset. The B10A has a quality analog front end with a noise rejection filter, some of the top end ZyXEL modem-routers but not all may have this too, but some definitely do not, so I am told.
The ZyXEL VMG1312-B10D is a cheaper replacement, which has a lower quality modem, so I am told, but this may not matter for some users - not sure if it even applies if you are using FTTC or if you have a very good line. Perhaps someone who knows what they are talking about would chip in?
I am told Billion has very good reputation.