Originally Posted by
Pegleg
If you can afford it, get one that has a metal interior pot (not ceramic). That way you can put the pot on the stovetop to sear the meats and brown the aromatics, then plop it back into the cooker, add the liquids, and slow cook away. The All-Clad has this option, I think, and there are a couple of others out there as well. Searing and browning are how you get deep flavor into a slow-cooked meal, so avoiding having to dirty a second pot is well worth it.
There are even a couple of new ones out there that can sear right in the cooker itself - the temp knob goes up to like 500 degrees. That's not only easier, it also means you can do things like deep fry in it as well as slow cook. I haven't used them, but I love the concept.
I couldn't afford the above, so I have the Cuisinart 6-quart cooker and it works great for me (though I do have to dirty a pot to sear and brown ingredients every time I use it). Get a big one (like 6 quart) - may as well have leftovers, plus it's super useful on Thanksgiving for making giant vats of stuffing.