I have been wearing the 2(x)ist Essential Button Fly Boxer for years and consider them a staple in my wardrobe. They aren't as fullcut as other types of boxers, but not body hugging either.
The Calvin Klein Cotton Knit Boxer isn't loose fitting like other boxers. It is body conscious, as they say, and has a functional fly front. These are great if you are wearing slimmer trousers in a thinner fabric and don't want to have blousy boxers on underneath. They also are have a lower rise make them ideal for low rise jeans.
This Unmder Armour boxer has a classic fit and is made of a light weight polyester/elastane fabric which wicks moisture and is anti odor. I have a pair of these and find them to be quite comfortable and good quality.
I love the 2xist Pima Cotton Knit Boxer because it is made with super soft pima cotton, if it wasn't obvious from the name. This boxer has a functional button fly and is relaxed-fitting. This makes a great basic boxer for everyday wear.
This woven cotton boxer by Calvin Klein is cut slightly shorter than a traditional boxer and has narrower leg openings. Additionaly this boxer sits lower on the waist making it perfect for guys who like to wear boxers but also like to wear slim fitting jeans and trousers.