Whats a good tube preamp?

I'm considering the VTL 5.5 TL the Audio Research Ref1, LS25 and LS16 amd the Conrad Johnson Premier 14, 17LS and 16LS. Which of those do you think to be the more transparent with Electrostats such as a Martin Logan Aerius being driven by a conrad Johnson Premier 11 tube amp
The Balanced Audio Technologies (BAT) lineup is great. I got a BAT-VK5i here a while back for a little over 2 grand. It has a really nice sound and doesn't compromise in any area that I can find (or hear).
I recently purchased a Welborne Labs Reveille Tube Linestage and love it. In a short review from the current issue of Positive Feedback magazine the editor, David Robinson, described this unit as having "low noise, neutral, with decent gain, precisely what you want in a fine preamp". I would describe the unit as being smooth, detailed with excellent bass reproduction. List price is $2,295. It also comes in kit form.
Sonic Frontiers Line 3 at the high end Audible Illusions as a bargain option.
"Sagger" is correct. New CJ has added low level resolution and lessened upper mid euphonics than earlier "golden" hued models (or even "dark" to some). Bass still a wee touch plummy, but exceedingly truthful. ARC - all of the new ones (which is why the iterations of REF I to II happened so quickly and why the VT 100 needed new caps & dampers) - are upper midrange challenged in a mechanically tinged way. If you run their pre's with ss or ARC amps or 6550-based amps, you wont notice the difference (please, ARC owners, save the railing). Like CJ, Joule is very dimensional, and each, with proper matching equipment, is capable of enveloping the listener. However, with that said, I believe Joule is a touch better with the illusion of the farthest depth field (which you probably wont hear without SE triodes and the right cables). "Sagger" again correct on "warmth" on Joule, or rather, apparent warmth. I would attribute it to lessened energy in the upper octaves combined with a still slight plummy tendancy in bass octaves that can be amplified in effect with wrong equipment (but still, like CJ's, very natural). On Joule, "Sagger" correct on model number (Mk III). Mk I's are vague and soupy, almost compressed; Mk II's much better, particularly at frequency extremes; but, Mk III with different driver tube in output stage & Purist silver wire to brighten things up just a tad on low level detail is best, and particularly regarding rhythmic energy in bass (also drives cable better). A fair price for well cared for Joule is $1800 and a no-brainer: hard-wired, NOS tubes et al. CJ has better name recognition and, accordantly faster resale, but a few more rubles. Properly matched, I dont think the Joule is lesser compared to the CJ's, even more liquid, perhaps, but less versatile from system to system. Joule REQUIRES a very good power cord to sound its best in midrange weight and rhythmic pace (another $500, remember...) .I havent A/B'd cords on the newer CJ pre's. Original copper Electraglide cord is good bet for both at $240 used, but a lot of people ga-ga now on the new Shunyata stuff, so you might ask around about those. Good luck!
Sagger, I'll defer to you on the neutrality of the current models of CJ. I do think that from a transparency standpoint, an ARC LS15 does sound more transparent than say a PV10. Perhaps that is due to (as Asa said) the "challenge upper midrange". No fight here on that. I've found a synergistic match in my system and I have ALWAYS enjoyed CJ gear, so as I said above, you can't go wrong either CJ or ARC. I have not heard, but hear from others, that Joule is top notch as well as CAT. Good luck.