Rangefinder vs. SLR. Very different shooting styles. If you haven't tried a rangefinder, I'd probably start with a less-expensive fixed-lens model and see if you like it. No reason to buy a camera that you don't enjoy.
As for Zeiss vs. Nikon, I believe many of the Nikon lenses were based on Zeiss designs. Or at least they were "way back when" ... before zooms and the (over)emphasis on high-speed optics. Anyway, I'm getting way off track.
I agree that there is a difference in the results from the two groups of lenses, although the differences narrow at smaller apertures.
And then there's Leica -- also a top-shelf maker of lenses and cameras for both rangefinder and SLRs. But they will most assuredly blow past your $1,500 budget.