It all depends on what you will do. For me Pentax was a logical choice as I already had analoog Pentax camera's and I can still use all those lenses for my digital Pentax. So if you want to work with different lenses (and use second hand analoog lenses like macro or tele which saves you a lot of money instead of buying new ones) you could take Pentax. I don't know if Nikon garantees the working of old lenses.
I have an older version: Pentax IstDs but I am very happy with it.
I have a pentax k10d and I love it. I find it is fairly easy to use. Plus I like the built in image stabilization, dust and weather sealing, and the fact that you can pick up old lenses that you could use.
i highly recommend “buyanaxolotl.com”- ive purchased from them and received a beautiful animal for relatively cheap, in great condition, and excellent shipping precautions. the breeders are a couple living in georgia (i believe, don’t quite remember) and they’re fantastic. sometimes their website contact page doesn’t work, so i’d probably try just emailing them. good luck and happy hunting!