Lots of variables – which airport is easiest for you to get to in the UK? Are you happy to hire a car at the other end?
For example – I live in Bristol and by far the easiest airport to get to from here is Geneva. If I’m going for a week, I don’t mind hiring a car so I’ll go for somewhere which is a longer distance from the airport such as Val, Tignes, Les Arcs, La Plagne or Three Valleys. Then I’d look for a self catered apartment on Airbnb or HomeAway.
Similarly, I can do Salzburg or Innsbruck for a week, but I’d probably do half board in a hotel in Austria (I’ve never had much luck finding SC accommodation in Austria) and the standard of hotels is very high in Austria IMO – rooms are bigger than French shoeboxes. In which case Crystal all the way.
If I’m doing a long weekend, then I’m stuck with Geneva and I’ll want somewhere close to the airport so I can get a cheap transfer – this means Morzine or Grand Massif.
Don’t worry about lift passes – they are easy to buy in resort.
Personally I’ve never booked a last minute package deal so I can’t comment on tour operators in that regard.