Talk about splitting hairs... C'mon guys. We're talkin' Zeiss here. It's all good. Some may be slightly better, but not without sacrifice.
First off, Leicaphiles will NEVER admit when their lenses are beaten; NEVER.
Granted, I have wished for faster prime lenses on my G series, but we're also talking about diatonic design philosophies. Zeiss and Leica are completely different schools of thought. Zeiss is about performance across the board. Leica strives to push the envelope of lens capabilities like huge apertures, again with some sacrifices like flare and, let's face it, super shallow DOF (out of focus) is not always useful or necessary. It may be dramatic, but F1.4 is plenty shallow and infinitely more hand-holdable. What's the point of a lens that's so large you need to use a tripod or support to get sharp images? You might as well shoot medium or large format if that's what you're really after. Talk about pleasant bokeh or DOF. This is'nt so much related to the lens maker as much as it is the circles of confusion a larger format lens creates. My Planar 2.8 for the Hassy is far more pleasing wide open than just about any 35mm super fast prime. Those lenses are trying to emulate the medium format look and they do well, but the devil is in the details. Resolution is }only 3.5 times greater due to the film/sensor plane and the circles of confusion created by those larger lenses.
To answer the question as to which five I would pack in my bag I would have to say that if money were no object, the 21mm Distagon is one of the most corrected lenses ever made, but you get insanely sharp images with the 25 2.8 or 18 2.8. And if you're after sharp you'd probably stop down anyway, so speed isn't the issue here. Of course if you are doing architecural work, the 18 may well prove to be more useful overall. With such sharp images one could always crop in for a tighter shot. Next, the 28 2.0 is a stellar photojournalistic lens, but heavy. After that, the 50 1.4, the 85 1.4, and the 135 2.0. I'm going to cheat here, but throw in a Zeiss mutar 1.4x and 2x and you've got a few more lenses that are still relatively fast and every bit Zeiss quality. Much lighter too than lugging around any zooms.
Don't buy into this Leica jargon like "micro-contrast" either. We're talking about light transmission through optical elements. T* coating is still the absolute maximum transmission of light from one end to the other. Believe me, all the details are still there, and then some, in Zeiss T* Optics.
Alas, printing is an artform inofitself. A master printer can make a Michelangelo out of a Lomo and most any lab can ruin the best of a len's capabilities.