I've been trying to make a similar decision.
Meta 5 – Had one, good fun, but I got bugger all for it when I sold it on, I won't do Commencal again.
ST4 – Seems like an interesting bike. Not as much of a mile muncher but more craic downhill. The spec isn't great for the money. Looks a bit funny.
Zesty – Everyone loves them, spec is alright apart from Formula brakes (first thing to break on my Meta). They have put their prices up – £2800 is list price for a 514 in 2010.
Trek EX, Stumpjumper, Trance – I'm sure they are all very good bikes but I am finding it hard to get excited about spending big money on them.
I'll probably buy the Zesty 514 or just start looking for good deals on frames to build the way I want.