I like 2x15 cabs. Over the years I've owned a late '80s Randall 2x15, an Acoustic 406, and an Ampeg B25B.
I liked the Randall at the time, but it was my first bass cab ever, and it was stolen less than a year after I got it. I didn't have anything to compare it to at the time, and I haven't seen or heard one since, so I can't really comment on its tone.
The Acoustic I had a couple years ago. Nice loud cab loaded with a couple of cheap Eminence Betas. A bear to squeak in and out of my sedan's back seat, so I sold it.
The Ampeg was pretty cool. Easier to get in and out of the car due to its shallower dimension. I removed the stock speakers and loaded it with Eminence Deltas. Sounded pretty good. Seemed to loose some oomph on notes below G on the E string. Notes in the mid-neck area sounded nice and fat, though. Ended up selling it due to that poor response on the lowest notes, which I figured was a factor of its design.
Right now I'm using this Bill Fitzmaurice designed 2x15:
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=180295626869
Only had it a few weeks, but I've played several gigs and rehearsals with it, and I'm really digging it. I'm definitely more satisfied with it than any of the others I've had. As you can see, it's a different design with the speakers loaded way back in the cab. It's clear and punchy and sounds great with my 200 watt custom tube head. It's loaded with Eminence neos, and it's light enough that I can heave it up over my head and onto my shoulders using the side port holes as handles. Carrying it that way, I am able to go up and down stairs no problem, as long as the stairwell is wide enough.
On the dual 1x15 front, I've used Edens and Ampegs. I really enjoyed the Edens. Haven't had them for close to ten years now. Sold them for financial reasons. Would love to hear a pair of them again, see if they're as nice sounding as I felt they were at the time. The Ampegs were okay. A little boxy sounding to my ears. Not a full, round sound like the Edens, but they worked in the mix alright. I probably wouldn't go out of my way to check out a pair of them again.
As a side note, one cab I've been using for several years now is an EV 18BX loaded SWR Big Ben cab. That cab with that speaker has given me pretty much everything I've wanted soundwise. The EV is loud and clear sounding with plenty of highs, while the lows are what you'd expect from an 18. I'm getting the speaker reconed right now, but I'm going to do a little side by side comparison to the Fitzmaurice cab once I have the Big Ben back up. Since the Ben's the cab I've used most consistently the last few years, it'll be a good reference point for my ears when listening to the 2x15.
Fun stuff!