Peet's Coffee is my favorite. But I've only seen them in CA and MA. Then again I don't travel to many different places in the US.

In America: Peet>>CBTL>Starbucks>>>>>McD>Dunkin (actually, McD is no better than Dunkin, but Dunkin is also overpriced).

Doutor Coffee in Jpn is my favorite coffee chain. Starbucks in Jpn are not that much different than in US, but their drinks are made more consistently well, they offer free self-serve syrups and the maccha latte is infinitely better.

Dunkin: so overrated. I used to live in BOS where everyone's got this inexplicable loyalty to Dunkin. Dunkin is overhyped and overpriced.

McDonald: also not good. Their coffee is often very bitter.

Starbucks: At least they're good sometimes, and they also provide you with a decent venue to unwind if you decide to drink in. However, sometimes their latte just tastes like hot milk.

Coffee Bean (only been to ones in AZ and at SEA): Coffee slightly better than Starbucks, although the latte at Starbucks can be better than the one at CBTL depending on who's making it at Starbucks. They definitely have better selection of tea than Starbucks.

Caribou: Only had them a few times... I didn't think they were that good.