I've never played a Washburn guitar before. I'm considering getting one and those Nuno series ones look cool. How do these compare to Gibon, Jackson, Ibanez and so on?

I've looked around and it seems there are like.... 15 different models of the Nuno series guitars. Some have that big N1 or N2 thing on them and I don't want that one.

http://www.youtube.com/watch?v=k16QPHUbmRM - the guy from Nightwish used to use these and it doesn't have that big N1 on it. I'd like something like he had, it looks like it's a floating trem with a locking nut without the letters on it. Which one is that?
These are the better ones with the stephens cutaway.

There are some cheaper ones, but they have regular bolt-on necks
2002 PRS CE22
2013 G&L ASAT Deluxe
2009 Epiphone G-400 (SH-4)
Marshall JCM2000 DSL100
Krank 1980 Jr 20watt
Krank Rev 4x12 (eminence V12)
GFS Greenie/Digitech Bad Monkey
Morley Bad Horsie 2
MXR Smart Gate
The American-made guitars are very well made. I cannot say the same about the cheaper, overseas models. The "Nuno" models may well be the longest-surviving models in the Washburn electric guitar lineup. They have been making them constantly for many years.
"Maybe this world is another planet's hell?" - Aldous Huxley
From looking around, the N4 seems to be the best. I'm going to buy a used one so is there a particular year that I should look for or stay way from? Or are they all pretty much the same?
No, you should be just fine. Washburn is a very old company, so they have been doing this for a long time. While not as popular as some of the bigger manufacturers, their American-made electric guitars are consistently very good.
"Maybe this world is another planet's hell?" - Aldous Huxley