If I could only have one bike for everything it would be a light small-travel full-suss like the Anthem X2. (Well... obviously the X0 if I had the cash...). Or possibly one of the Boardmans- excellent VFM. The lightness for climbing and handling, the full-suss for simple enjoyment on descents and comfort on all-day rides.
But bike garages are an evolutionary thing so you end up with different things for different reasons! I seem to have ended up with a full-suss trail bike for centres and having fun locally (Commencal Meta 5, 140mm), a light geared hard-tail for all-purpose local riding (Scott Reflex- bit stiff though) and a singlespeed hard-tail which is fine for all my local stuff, Surrey Hills included, and I find I ride it nearly all the time now (Dialled Love-Hate).
An Anthem would still fit in there nicely between the Scott and Meta, but with a small bundle of joy on the way finances can't stretch to it just now!
But a decent rider on a decent hard-tail can still ride anything bar the biggest drops. Couple of mates (both with Cotics incidentally which may or may not be something to do with it!), have used them in anger where I'd personally only take a full-suss (black trails at Laggan & Golspie, and the DH trail at Cwmcarn).
What I would definitely say is if you can, test-ride the bikes before you buy. Preferably head-to-head. Best thing I ever did. You end up a right bike critic though- it really amplifies the differences between them. I tried a Heckler, Yeti 575, Marin Wolf Ridge & Meta 5 which on paper all have similar amounts of travel but use it in really different ways. Should have tried some different bikes in there too like the Orange 5 and Lapierre Zesty.
What-ever you end up getting, as long as allows you to enjoy riding the most, that's what counts
And while we're on the subject of riding, here's a clip from a trip to Scotland 2 years ago... (select 480p for better quality)