Some of them are great if you don't mind a bit of work, and etching new panel lines.
I've been disappointed by a few Hasegawa kits I've built lately - OK the detail's great and the fit is largely good, but the ones I built were let down by poor kit design in some areas and, in a few areas, very bad fit. Plus I couldn't help thinking I'd like to make something I have to put a bit more work into, rather than a kit that virtually falls together when you shake the box.
Anyway I tend to go for the subject, not the kit, and Monogram produced kits of a few subjects I can't see Hasegawa or Tamiya coming up with in the near future. Where else are you going to get an F-101, F-105, F-106 or Panther in 1/48, for example?