RSE had the Lati twins, which are some of my favorite legends, period. It also had Jirachi. But I didn't like Groudon, or the Regis.
I liked every legendary in GSC except Entei.
DPP had too many goddamn legendaries. I liked the psychic trio, but they were underwhelming. Shaymin is probably my favorite legend to come out of this gen, otherwise, I probably disliked this gen the most.
RBGY's legends are all ones I like, but they've mostly fallen off the radar.
BW had the muskedeers, Victini, and the therian form genies. I REALLY liked all of these, however I didn't care too much of the others.
"Religion keeps pressing B when we try to evolve." - pirategeorge" [3DS FC: 1934-0673-9848 (Pentao)]
Gen I: Solid, but lacks variety, since all of them are either Flying or Psychic. Gen II: One of the best, with some very great designs, but it's held back a bit because I really don't like Ho-Oh. Gen III: The Regis aren't very interesting, but the rest of them are really good. Gen IV: This is the point where the series started going overboard with legendaries, and it's not really helping it. It's got some gems, like Darkrai, but the most of them are so...average. Gen V: Pretty much the same issues with Gen IV, and it still has the annoying trend of making all cover legendaries Dragon-type. In the end, some are very good, but most are just ok.
So in the end, it's a toss-up between Gen II and Gen III for me.
Oooh, MM, he be tryin' you, dawg. He be tryin' you. Best mind you biiiiiiiz-ness. ~KMA *triple z snap* ~AluminumTicket