I like the Tully Italian Roast and Green Mountain Sumatran Reserve...
I've tried a few others, including donut shop, newmans, and some of the other green mountain roasts and thought most of them tasted bitter and had an unpleasant aftertaste.
The first machine I had (similar to keurig platinum, bought it as a kit at BJ's), had the pump fail within 30 days. Returned it to BJ's, that one lasted about 6 months and Keurig kindly sent me a new one, didn't even ask for the old one back. This latest one is probably about 18 months old now.
Two things I really dislike about keurigs are the price of the Kcups, Im averaging a over $100 usd a month on these puppies, and the fact that the kcups are not recyclable.