after watching both series several times i can safely say that Rah is a stunning series and does pretty much everything right: likeable characters, mesmerising visuals, great story...unfortunately it is, as has been pointed out already, derivative. still, at least it was inspired by stuff that's really good: the likes of NGE and Gundam.
Eva on the other hand has a number of good reasons why people dislike it. psychobabble, a few irritating characters and one metric tonne of hype that goes along with it. so, why do i prefer it? the answer is, to put it bluntly, balls. the director's i mean.
Anno created soemthing so over-the-top, self indulgent and pretentious it's a miracle Gainax didn't go under. the story was obtuse to the point of being incomrehensible and yet he had the sheer hard-nosed determination to vent all his frustration and dispair into a TV show.
yeah, i find Shinji whiney and annoying, but as much as i want to clobber the spineless little git i realise how likely i would be to make the same mistakes in the same situation. he's the wimpy, childish side to all of us in that sense. the rest of the cast are unrealistic but have had an immesurable effect on how anime was done since.
then there's the way the series was created: sure, the characters don't develop but certainly go through one hell of a lot and teach the viewer more about life than they themselves learn. building up what seems to be a dumb mecha show with a 'monster of the week' turns into something much darker, experimental and original later on: all of a sudden it becomes an exercise in sheer mindfuckery with a labyrinthine plot and visuals that arepretty damned amazing for 1995. like i said, it's very over-the-top but i can't help but admire the guts that went into producing it.
sorry if i went on a bit there. both RahXephon and Gunbuster are still excellent shows that every self-respecting anime fan should see!