In reply to Martin W:
29" on a hardtail is ideal for gravel/tarmac routes with the odd bit of "mountain biking" on singletrack etc.
27.5" is better for smaller people (many bikes will only come with 29" wheels in size medium and above) and more big mountain/backcountry riding (IMO)
650b/27.5+ is a compromise between the simplicity of a hardtail and the comfort of a full suss..
Having been riding an Orbea Loki + bike for the last 10months (it became my go-to bike, soooooooo much more fun than my full suss), then having a crack on my mates steel 29" hardtail last week, the extra grip, comfort and cushioning of the + size tyres was instantly noticeable. I thought + tyres would be a fad, even when I bought the Loki, but they're here to stay, and with good reason.
1x set ups are great for faff free riding, but if you're doing a lot of backcountry riding, as opposed to trail centre, 2x set ups still get my vote for grinding out the long ups and blasting down landy tracks on the way home.
Whatever you get, for £800-£1000, it's tough to find a crap bike these days!
EDIT - the dropper post question - possibly the biggest leap forward in mtn bike technology in the last decade, they have revolutionised riding. If you don't get one with your bike, and don't have the big bucks to buy a fancy one, the Giant Contact one is good price point and fairly decent quality. Alternatively, check out teh Orbea Digit seatpost - not a dropper as such, but as close as you'll get to it without the weight penalty and the problems you can get with hydraulics/stuck cables etc.
Post edited at 23:43