budget will be limiting factor, so you might want to look at used bikes on PinkBike.com or some other MTB forum. There are tonnnns of good bikes out there. I've had a Kona and now ride a Transition Scout, and I love it. I started with a 29er, but went down to a 27.5 because it was a little more playful.
You should consider what type of trails you be riding, as you'll want to consider that to choose your bike. For example, the Kona Process 165 mentioned above is a solid bike! But it has a lot of travel that is better suited for big mountain and downhill riding. My transition scout probably has too much travel for most of my local trails.
Whatever bike you get, if you end up liking to ride a lot, you'll catch the upgrade fever quick! Good luck!