I like when people brag about themselves, especially at work when I'm still a fledgling member of a large career world where titles don't tell you much. I think you can brag in non-arrogant ways, but in "I'm proud that I've done x" ways, that say, "I've made a name for myself in xyz subarea" accompanied with "I don't know much at all about abc."
If everyone's too humble you can't figure out what's up. Own your competency, just don't be afraid to admit areas of unfamiliarity.
Also, people who are genuinely pleased with themselves are much more fun and interesting to be around than people who are always bumming you out about how they don't measure up.