The 767 is an older plane than the 777. But it has an excellent safety record.

Prior to the 767, most aircraft that flew transatlantic were four engined. The 767 revolutionized long range twin engine operation, paving the way for later aircraft such as the A330, 777, 787. The 767-300ER has enough range to do west coast of the US to Europe, so flying it across the Atlantic isn't an issue.

Obviously, things vary based on how airlines decide on how to outfit the cabin, but I think that generally 767 is the comfiest airplane in economy class, which is a 2-3-2 seat arrangement - 85% of the seats are either aisle or window.