TalkTalk supply a number of router's for their service, which they might admit that they are not the best, but more than adequate. I have used a variety including Thomson (better chipset?) and at present a Huawei EchoLife HG520b router, supplied by TalkTalk.
Because TalkTalk use a LLU system, there are router's out there with better chipset that are perhaps 'better' for LLU. I use to have a data list, covering this subject, but at present I am unable to find it. You might find something here though http://www.kitz.co.uk. But be prepared for a heavy read or trawl!.
It might also pay to check TalkTalk's own forum, to see if there are any specific recommendations being posted there.