I had the First Sound in my system for many months - I know people who love it. In my system, the FS was very good but ultimately a bit leaner than I like, and I didn't realize by how much until I put the Herron in.
Remember, I was using the hot-rodded version of Keith's original preamp - not the 2, the 3 or 3a. The FS is excellent, excelling most comparable pres in bass and dynamics. But I felt the Herron had all that plus it was just...rounder...more natural sounding...totally effortless...just as dynamic...it's very hard to describe the differences actually, because the Herron gear doesn't really have a "sound". How do you describe the "flow" of music Herron achieves??? I haven't heard anything like it except with ginormously expensive components. While I was listening to music through the Herron I wasn't aware of anything missing at all - the sound was "whole". Completely satisfying.
Now, having heard the VTSP2 and 3, I know that those models do in fact improve on my pre - better bass, solidity, dynamics and air...but again, I was never aware of those qualities being lacking in the slightest with my pre in operation...even Keith's first preamps produce music of a whole cloth, very satisfying.
Lastly, and this might be a small thing for most people, but I also preferred the ergonomics of the Herron over the FS. It was just easier for me to use.
I loved my Joule Electra LA 150, as I'd loved the LA 100 MkII before it. The 150 is a wonderful preamp...as is its predecessor, but it's definitely on the warm side of neutral. Not by tons, but it defintely is. You can get it custom tweaked to suit your system, and it does better with an after market PC too (that tends to wake the J-E's up a bit).
I could've lived very happily with the Joule. I describe it as making music "more beautiful" than real life, and many people are seduced by this quality. If the FS and the Joule are the yin and yang of the audio spectrum, then the Herron is in the middle. But the Herron definitely beats the Joule in dynamics and top end, especially in big, complex orchestral music.
Never heard the Lamm in my system, and I would imagine it is superb, but possibly more system dependent than the Herron.
I think Keith makes killer preamps and amps for very modest prices, especially considering the quality. Not statement pieces, just amazingly musical gear. He and his wife are true music lovers - the Herron room always sounds excellent at any audio show, no matter how bad the room, no excuses, just good music. That's the kind of philosophy I can believe in.