One station which I don’t think has been mentioned yet is Finsbury Park. Another place which has become almost horrific to use over the last couple of decades. Awful place, both NR and LU.
FPK has seen a few improvements over the last few years, but none of these were holistic solutions to the ills of the station. There are now lifts to all platforms, and part of the original concourse has opened as a tunnel at street level.
The lack of gates previously made it an attractive station for druggies and beggars to use to access the network (the area has a reputation of being destination for buying drugs). It's now properly gated at all entrances (rather than at the top of the stairs on the NR platforms). Those wishing to not pay just jump the barriers with staff seemingly not caring.
The New City North Place entrance has seen the grim Wells Terrace tunnel replaced with a proper, gated ticket hall, leading on a new street with retail and cinema. Just about every expense seems to have been spared on finishes in the ticket hall, an its interface to the rest of the station.
The Seven Sisters Road tunnel still remains, and along with the NR passage, leak when it's wet. The former, with Sewage. It's been closed all week.
Station Place is still sketchy - invariable at night there is a group of black-clad, hooded youths smoking weed in the bus station - which is fairly intimidating. The TFL surface transport bye-laws apply here (same as the railway byelaws - so offences for begging and loitering), but it's at the boundary or Islington, Haringey and Hackney Met Police divisions. The BTP have an office about 200m away. Between them. they can't work out who should police it.
The station needs a London Bridge style reconstruction, but even in its current state, there are far worse.