In the end it kind of depends on what you want out of it.
Kraken:
Pro:
- Cheap
- Described as a "3D instruction guide with screws that you can play with while upgrading slowly"
Con:
- High Failure rate (which is why you want to upgrade certain parts right off the bat and upgrade other parts over time)
- Need mechanical/electronic knowledge (so either learn to do things yourself fast or find a gundoc)
DPMS:
Pro:
- JG quality (not bad per se.... but not really good either)
- Lower failure rate (however you'll still probably need to learn about electronics/mechanics eventually).
Con:
- Bit more expensive and for a little more you can get a full black gun from a more reputable brand name (in the classifieds).
If you like taking things apart and trying to tune things to get better performance (I'm an OC'er and I like taking electronics apart to try and repair instead of sending it back to the factory or paying someone else to repair it). Then Kraken is probably the better choice.
HOWEVER if you just "expect" things to work (Mac: It just works....
.... yeah... ) then the DPMS is probably a better choice however you'll still need to eventually find a gundoc or get some mechanical knowledge.