If you have money to spend get the transition double.
If you dont have money to spend and want a dj'er for under 300$ buy a used fork on craigslist and slap it on this 26" DK Xenia.
fuck dj.....................i had plenty of friends with them, but they get bored with them quick
get a hardtail with 4-6 front suspension
You are just getting into the sport.
2010 Specialized Rockhopper
2013 Kink Launch
2004 Haro Backtrail
2004 Nirve Dig
My rockhopper suits all my needs from ridges and headwalls to park jumps.
If you actually want to jump get a bmx bike.
Kirill Benderoni 2010-2011 on Pinkbike
I live in PC and ride all the time- XC, DH, and a little dirt jumping. The truth is that there are very few trails in the PC area you need a full on DH rig for- Thieves and NCS at Deer Valley come to mind but pretty much everything else can be done on a freeride or even long travel XC bike. I had an older Turner DHR (true DH bike) that I recently sold and picked up a Specialized Status- 7" of travel, can do short climbs if necessary, and is a lot lighter.
As others have said, there is no such thing as a killer DJ/DH bike- DJs have very little (if any...) travel and are only good at one thing. Conversely a long travel DH bike is going to absorb your energy going into those jumps and not really give you any pop.
Look for something in the 5-6" travel range, preferably used off Pinkbike or KSL in salt lake. Given that you're relatively new to the sport there's no need to spend big money on a new bike.