Left wing here but hate the new names, i much prefer geographical names but that is because i value practicality and substance over style. Perhaps my least favourite ine is the Mildmay line, how does that in any way represent those on the western ends of the line ie, Richmond Branch, West London line branch to Clapham. Theres not a station on the line called Mildmay, the place its named after Mildmay hospital is nowhere near the line.
Goblin line
Harlequin/Watford DC
North London Line/ North London Orbital (with West London branch specifically for trains to/from Clapham)
East London line/South London Orbital
Tottenstow lines
Emerson Park line
Those would be my suggestions. These new names do i agree seem to politically motivated which doesnt fit well for public transport which should be open and accessible to all, and thereby not promoting one ideology or another. People have already mentioned the issues with windrush line favouring one subset of immigrants over others, a lot of the names seem to have very weak ties to the places the lines serve. Sure the lines needed seperating for increased customer clarity but for me the way they've done this i cannot get behind it. As i say Public transport, it should be open and accessible to all. The fact this thread has got highly political indicates that these names are not inclusive for all. Politicians building monuments after themselves is not a good use of public resources, be they left wing, centre or right wing.