First of all I much prefer loose tea to teabags. Much more variety, better quality, and better flavor all point to loose tea.
That said, teabags are sometimes simply more suitable to the task at hand. They are easier to take with on any trip, are less hassle to prepare, and don’t require bringing extra tools along that also need to be brought home again.
One of my preferred brands is Ashbys of London Tea. They offer a reasonable selection of black and flavored teas, as well as a few herbal and green teas, and a nice variety pack. The bags a individually foil wrapped (important to maintain freshness when traveling).
Check them out at devotea.com/Ashbys/Tea/