Back in RBY, I liked Articuno better than Zapdos or Moltres just because it looked pretty (well, that and Ice is a hugely useful attack type.) Articuno was the only Legend that had a regular place in my teams. These days, though, Mew's ability to use all TMs and HMs is more of a draw, especially since I can now get Mew in RB without a cheating device. Practically every runthrough I've done in Blue Version since the Mew Glitch was found has involved a Mew as an HMer.
I don't think I ever really considered using the GSC Legends much. They were trophies to be obtained, not battlers to recruit and train. I thought once or twice about doing a runthrough with a Game-Sharked Celebi as my main battler, just for fun, but never got around to it.
Come to think of it, I feel largely the same way about RSE and DP Legends. By the time you can get them legally, you've probably already built a powerful team, and bringing in a newbie is more hassle than it's worth. Maybe I'd feel differently if I had more exposure to link battling, but battling other humans just hasn't been something I've done much of since RBY, so ingame has been my Pokémon experience.