My large cooker is a Hamilton Beach, but without the bells and whistles DougR described. I've been very satisfied with it. Probably the only slow cooker I ever was displeased with was a 6 qt. Rival. Never could manage to cook anything properly, then it partially died while cooking a batch of soup - raised it to just an ideal temp to accelerate bacteria growth and sour it. My small cooker is a Tayama and it's been very serviceable as well.
In SC where we winter I have a Cuisinart 4 qt. programmable which I really like. The only thing really programmable about it is the time, but it has a feature of starting out at high temp even when set to low, until the food temp reaches 150. This more quickly gets the food above the temps ideal for bacteria growth.
Although I have round pots for the smaller cookers I use both in MI and SC, the larger pots have oval crockery and I agree with the other comments here about oval being better. Comments I've also noticed about cookers with digital controls is that the controls seem to go bad far too frequently. No good having a heating unit that works if the controls don't. Mechanical controls seem to have a far better life expectancy.