Out of the motors you listed I would definately have to say the RB26 is going to be the best bet for ease of install, reliability, and power. If you are looking for more bang for the buck though and don't want to make 1000 hp, the rb25 is probably going to be the better choice. This is what I am going with...should have it in the car within the next 2 weeks....just waiting on a z31 rb20 pickup. I got a motor set for $1950 shipped to me. Going with a standalone, custom header, and intake manifold so I am selling everything off I don't need from it right now on ebay. Should have less than $1500 in it for what I needed which is the long block and transmission.
If you have the resources to build a custom header, the vg30dett would make a nice swap for sure. Mounting it shouldn't be too hard if you put a single turbo up front rather than the stock twins. Can be had for a very decent price nowadays and will make an assload of reliable power as well.
I was looking into this swap before I found the deal on the RB.
JT