Of the 3 that I own / play, 2003 Spector ReBop4, 2006 Spector Euro5LX and 2006 Fender Precision Bass, the ONE would be the Euro5LX for sure. While I enjoy playing the other two, that one is my favorite. It's a combination of the feel, playability, tone, response, looks, comfort, build, quality, you name it.
Now, if I were to choose the ONE from any bass on the market and I has the bucks for it, it would be a USA built Spector 5 string, through neck. That would be more of what I already like about the Euro5LX.