Hmmm, probably whoever has the best chance of booting out Tory Girl Trevelyan.
The seat (as Berwick upon Tweed) was Liberal, then Lib Dem for donkeys' years until 2015. This was partly a backlash against the Lib Dems, but the Tory vote also increased. Labour have been the second placed party recently, but have put up a couple of PPCs I will not vote for (local councillors who I have found to be less than honest), so it depends who they put up this time, but I still remain reluctant to vote Lib Dem as I have not heard any apologies for what they did between 2010 and 2015 and I have a long and vindictive memory.