Been using 271mk1 for the last 5 years, they are good cans, well built, comfy, the bass is there, but its not hyped. I also really like the ATH M50's, again well built and comfy but they have more bass. Never used Ultrasone.
Generally I'm a fan of AKG cans, I had the old 240's for 12 years before the 271's, never a problem that says a lot, I've had (cheep) Sennheiser's that broke after 1 year. I'm thinking of getting the k701 or k702's next.