What factors do you consider when buying a new mountain bike?

have a hardtail at the moment

You have to know what kind of riding you are gonna do now, and in the future. If you are a casual rider who is out to get off-road and just tool around the country, then a hardtail with a no-frills fork will be fine.

If this bike will be your only bike and you want to ride some pavement as well, then you should also go hardtail and consider saving some $ for a set of road wheels, too. A fork w/lockout is nice for the pavement. Thats where I am at now, but I plan to become a 2 bike owner this year. Two sets of wheels is very nice so you dont have to abuse your knobbies on the pavement(I HATE riding my Velociraptors on even 1 foot of pavement).

If you are planning to use the bike only off-road, then you have to decide whether the extra cost and maintenance of a full-suspension bike is worth it to you. I ride like h"ll when I go, yet I cannot justify a full-suspension bike's cost and upkeep. I'd rather get a hardtail and spend some dough on the most important parts of a bike: wheels and cranks.

Lastly, I look at brands. Most of us like certain brands better than others. Its a long-term investment, so you have to buy a bike that you can be proud of that gives you a warm fuzzy. And of course it has to be a cool color. Then you find one thats within your budget, and let the fun begin....

First: Usage. What type of bike suits your riding style and environment.
After that you need to balance performance, quality and price. Everyone would love to have a bike that weighs nothing, never breaks, works flawlessly and is free but that's not reality.
Decide what your budget is and buy the best bike you can afford.

i would look at it in terms of what kind of riding you will be doing most frequently. for example, you may want another hardtail because you often ride on the roads as well as offroad. on the other hand you may only ride your bike offroad in which case you should buy a full suspension bike.

i believe it is important to assess the comfort of the bike because if you are not comfy then you cannot enjoy the other features of the bike. comfort is priority!!

also, be sure to set a budget which you can work to and buy the best bike that suits the budget.

hope this helps!

Before I buy a new bike or big ticket items for a current bike, I look at why I'm doing it.
1) Is the technology better than what I currently have?
2) Is it lighter or more suitable for were I'll ride it?
3) If it's a complete replacement bike, am I better off up-grading what I currently have?
4) Do I need the whole bike or just a new frame?
5) Am I just tired of the bike and need a change?

The last and I mean very last last thing should be price, If you have to ask can I afford it, the answer is most likely no.

is nice to find bik wit no deseses somtimes i feel is hard to find god stuf in worlds so full of the deseses but if use wips will help