Hi. No idea about different brands but there are different sizes available. Make sure you get a size that will suit a family (or not) sized portion. I like mine for making beef and lamb tender but think it tends to intensify the flavours so it can be a bit ready meal-ish. That said really easy and great for a no fuss supper esp in the winter
Oh, and the other thing I'd add is that it works best if you're big meat eaters. There are veggie recipes for the slow cooker but it works best for meat IMO. We don't eat that much meat and our DS can't eat tomatoes, which seem to be the staple of most veggie stew type things, so I don't use my cooker as often as I might. It's very useful for making stock overnight though.