If there's a particular style you're looking for that would probably narrow down the search a bit.
This is beer we're talking about. Why would you want to "narrow down the search"?
But seriously, Bells make wonderful beer. My favorite is their Pale Ale, but you want something darker. As noted above, the Porter is great and the Two-Hearted Ale is pretty delicious. Also try the Third-Coast Ale and the Kalamazoo Stout.
Chad