I use my Soundtracs MX "Custom"... 36/8/2 (plus 4 matrix). It deos everything, but they're as rare as hen's teeth and you need to have a lot of time on your hands to bring them back to life (Had mine 2 years and only jsut ready to close up the last 4 channel strips...)
Xstatic mentioned the Venice... I'm not a big fan of them... cheap chinese gear with a Midas label... (same with the Verona and the Sienna). But, without the money to spend on something bigger, they're OK I guess (although the aux section does leave a bit to be desired, and they don't handle heat too well- you'll blow the thing up if you use it above aobut 40 degrees). Whilst we're on the topic of Midas, they are looking to release a set of dig boards later this year, and, in keeping with their Venice/Verona/Heritage way of thinking, they're releasing three lines- a uber-high end that will cost trillions (well, probably US$300,000), a mid-range one and then a "budget" version which will fill the market for Venice-size dig consoles. Probably going to cost a bit, but it might warrant a bit of watching by people like us...
any console with 24 ch of ADAT pipe is going to cost a bit. A O1V-24 has got 8 ADAT channels I/O (2 pipes) and costs around $2k US. In the price-range of hte Onyx 1640, you're much better off looking an analouge over a dig.
It might also be worthwhile looking into getting the DA/AD converter upgrade from Alesis. They soudns pretty good (although I bought an XR striaght up, so I can't give you a comparison, sorry).
Anyway, I guess any of the consoles mentioned here would be good... teh Ghosts are good fun, as are the old Soundcraft Studio series- i stupidly let one of those go for a song last year (I had a rough couple of months and couldn't afford to keep two 24-track consoles, and the Soundtracs wasn't ready for sale at the time).
I also am a big fan of the A&H GL series, a 2200 would probably suit you, although it's only 4-bus, but with 4-band on every channel and 6 aux mixes, plus the whole "swap group/aux" thing, it's a bit of fun, espically if you're planning on recording anything live
Well... that was a long way around tosaying "just buy what everyone else said to buy)