Bacon, sautéed until crisp and then chopped up, is a great option for mixing into baked beans. Pulled pork, beef brisket, and chicken thighs also make excellent meaty additions.
Caramelized onions and a dash of something full-bodied — think a teaspoon of espresso powder or dark cocoa powder — will add an earthy depth to canned beans.
You can kick the heat up a notch by adding diced jalapeños or even spicier fresh peppers. Chipotles in adobo or just red pepper flakes are also easy options.
For a more complex spiciness, try Thai-style Sriracha hot sauce. A teaspoon or two of will contribute a hint of smoky sweetness with some considerable heat and a garlicky bite.
If you want a depth of flavor without heat, consider adding cumin, smoked paprika, and chili powder. These spices emphasize the smokiness and contribute an earthy flavor to beans.
In the end, if you still don't think canned beans are satisfactory, a good slow-cooker baked beans recipe is for you. It will give you delicious beans with no off or tinny flavors.