Are we just talking musicals? Then my best and worst this year is simultaneously
Too Close to the Sun. The first act was dire beyond imagining with no redeeming features (alas, I did not go on Tablegate Night

). The second act was like they looked back at what they had, realised there was no way they could improve it, so went all out and made it a hilarious experience. I've laughed a lot at the theatre this year (as an obsessively quiet little audience member, that really means something!), and at least half of it was act two of
Too Close to the Sun. :3
Or if you want a real answer, I suppose I enjoyed
Spring Awakening a whole bunch and am sad it didn't last longer.

When did
La Cage actually hit the West End? I've loved it every time I've seen it this year, but am trying to keep my choices to things that actually opened this year.