Having (re)watched all three Wright/Pegg/Frost films within the same 24 hours, I will venture that:
1. Shaun of the Dead has the most classic lines and references.
2. Hot Fuzz was the funniest and most generally enjoyable to watch.
3. The World's End seemed the highest budget with the most action:...
Aside from fleeting cameos from conical iced cream lollies, The World's End imported little from it's predecessors, beyond the falling over a fence gag and the cast (notably Bill Nighy as the authority figure who Pegg's lead rebels against). Apparently there was a deliberate exclusion of external references and influences in production, so be warned, this is not a Spaced style geek-out.
I might have found more delight by entering the cinema totally plot naive; while the trailer did a very faithful job of portraying the nature of the film, it did so at the expense of telling most of the jokes and the entire story, baring the stilted conclusion, which I found dull - too earnest to swallow as satire.