After 20 years since the last one I had, I've decided to get another standalone drum machine for jam sessions and occasional live performance. In addition to standard kit instruments I'd also like a selection of percussion instruments, e.g. congas, shakers & tambourine.
 
Since it's mostly for improvisation accompaniment, I want to be able to quickly pull up a patch and go, and to switch patterns and throw in fills using footswitches. That means an easy-to-read display, minimal menu navigation and a dedicated knob for setting the tempo. What I don't want is to pre-program song arrangements. It probably won't ever be used for recording, just live jams.
 
Here are the ones I've looked at so far...
 
Boss DR-3
$189 but does not include footswitch or power supply so not as cheap as it first appears. Small, dimly-lit LCD display and requires navigating tiny menus to do anything. 100 factory presets and 100 user presets. Potentially clever intro->pattern->fill->pattern->end sequences.
 
Alesis SR-18
$259 but includes power supply (and maybe a footswitch but the Sweetwater description was not clear on that).
175 factory presets and 100 user presets. Nice big dial for setting tempo. Has EQ and compression but they're just presets, not tweakable. Volume control is on the back (WTF?).
 
Zoom RT-223
$149 but power supply and footswitch are extra. Has the most variety in drum sounds (70 kits) and the largest number of factory presets (440). Volume control is on the back.
 
 
All three let you control them via footswitch, but I don't know how well. Two of them offer a hokey-sounding bass synth that still might be useful for impromptu jams. 
 
I'm hoping somebody who's used one or more of these can offer advice on aspects I can't research online, namely how effective they'd be for my intended purpose. I need to make this purchase in the next 2-3 days, so any insight will be greatly appreciated.

i used to use a zoom 123 (still have it)
 
it's a great little machine.
 
i recorded a lot of demos using drum tracks from the 123
 
i don't know if it would do what you need, but i'd be willing to part with it (for a nominal fee!)
find it, if interested, PM me for info

I still have my Zoom Rhythmtrak 234 as well. When Zoom first hit the scene they came on very strong in performance. I am not sure if they maintained that perception over the years, but the brand carried a lot of weight back in the day. I am sort of confused how they "number" their products though, since I bought the 234 20+ years ago, and you have the 223 linked.

While I don't have the Alesis SR18, I've got a friend that perform with it extensively and he can operate the fills and pattern change easily with the pedal. I'm not sure about the other units, but for the Alesis SR18, you can trigger the A,A fill, B and B fill.
 
Have you check out BeatBuddy ? I used to think it's not flexible with only one pedal, but I after learning that you can add additional foot switch, I think it's quite capable too, but it's mainly placed on the floor. I would still prefer a table top unit.

The Zoom 123 is apparently the predecessor to the 223, which kinda makes sense. Where the 224 fits in I haven't a clue. I've read some online comments where users preferred the 123 to the 223, just as many prefer the older Alesis SR-16 to the newer SR-18 (both are still available). It's reassuring to hear that people have 20-year-old units that are still working.
 
My initial preference was for the Zoom, as it's the cheapest, but I may not be able to cope with the small orange display. It looks like the same display used on my XK-1, and that one's so hard to read that I never dare making adjustments while I'm playing. Otherwise, I'd take you up on that offer, batsbrew. Maybe I could tape a magnifier over it...
 
I took another look at BeatBuddy ($328 w/footswitch at Sweetwater). It had looked interesting because it's clearly designed for live accompaniment, but I'd crossed it off the list because there's no congas, shakers or tambourine. It does have a brush kit, though, which is cool. It's also pretty cool how you can create MIDI patterns on your computer and transfer them to BeatBuddy.
 
(Sigh) I remember a time when I didn't stress over a $200 purchase...

I did a quick search on that, and still confused. There is a 4th model (RT-323) also listed in their manuals (http://www.zoom.co.jp/downloads/ (third up from bottom)). I think the 123 has the biggest display of the 4, and looked reminiscent of a giant red LED clock, but I do not see the parameter slider that the 234 has (i.e. no hardware dedicated to quick adjustments). Actually, just realized that the 223 doesn't have it either.... Hmmmm.
 
IIRC the 123 and 234 were sold within a couple years of each other, with the 323 then hitting the scene will more "goodies" a few years later. No idea when the 223 came out though. The 323 display looks the most micro-scopic of the bunch.

You can find SR16's cheap. I got a "new/unused" one for $65 with PS, manuals and box. If there'd been an SR18, I would have tried that, since I've had a series of "16's". My wife and I use it, and I practice with it,  and might try to work it into my track creation. I'm not sure about that, though.....
Another possibility, is the DigiTech Trio which does bass and drums for $179 street.
http://digitech.com/en-US/products/trio
 
Michael

I saw an SR16 for sale at a music store I was showing a roducer friend of mine in Ho Chi Minh, and we couldn't believe that it's still in production. Credit to it that it's still going after 2 decades with how much so much has changed along the way.

Kamikaze
I saw an SR16 for sale at a music store I was showing a roducer friend of mine in Ho Chi Minh, and we couldn't believe that it's still in production. Credit to it that it's still going after 2 decades with how much so much has changed along the way.

A good design will last. I've got the Boss DR 880, in term of sound, it's way better than the SR18, but in term of live usability (fill, etc) it's worst than the older DR series.
 

That DigiTech product looks very interesting indeed. It's like Band-In-A-Box in a stomp pedal. I'll definitely try that one out if they have one at my local music store. Not sure it'll adapt to my style, as my short attention span never allows me to play more than two chord progressions in a row.