WGS suggests their models are similar to specific Celestions on their website. I have found them to not be similar IMO. I have a 2X12 cab w/ a WGS Retro 30 and a Reaper HP and another cab with a Celestion V30 and G12H. Celestions are much brighter to my ears, WGS much warmer. I like both pairings, but use the WGS more frequently, so I guess I'd conclude I like the WGS a little more. And the comment above about WGS taking forever to break-in, I must agree with...probably 100 hours at around 95 to 100 db.
As for Celestion 70/80, I like it also, but again, it's brighter than the WGS.