Like most people here (which is honestly a bit of a surprise to me), I don't like to use Legendaries. It's less the fact that they're overpowered and moreso the logic. It just doesn't feel right for some ordinary person to subdue an all-powerful godlike creature and force it to do their bidding. I do catch them for the Pokedex and collection purposes, (and also, so I can trade them anyway if I want something else), but I just don't want to be steamrolling over everything with a creature I shouldn't even have. If Pokemon were real, it would be certain that people would likely not be able to capture Legendaries as easily in the games. And I prefer to be immersed rather than breaking that.
Of course, there are some Legendaries that are more down-to-earth and not really so high concept, such as Kanto's birds, Johto's beasts, the Lati's, etc. These are more so Pokemon I categorize as Demi-Legendaries. Which are not really godlike beings so much as really powerful Pokemon. Although I haven't used any of these (mostly because they're obtainable really late in the game by which time my party is full), I wouldn't really have many problems doing so.