in terms of pokemon:
gen 3 is boring as fuck honestly. only a couple of interesting mons (i can honestly only remember breloom and sableye right now), most of them are just plain boring, and a couple of ugly ones too. most hoenn megas suck, which just proves my point.
gen 4 at least has cool evos like mamoswine, togekiss, porygon-z, magnezone, weavile... etc etc i could go on. and a couple of cool original mons like abomasnow and toxicroak. if heatran was a pseudo or like volcarona, you fat asses would love it too. and just the physical/special split makes it much more interesting.
in terms of gameplay:
both evils teams are stupid and ridiculous, instead of just using their own means they go out of their way to use uber shit they don't even understand. magma's and aqua's plans are just plain silly, and cyrus' is ridiculous, but then again the point is that he's half crazy half autist. pretty much all of the gym leaders in both these generations are completely forgettable. i can't even remember gen 3's plot, everything is so forced up your ass, i know there are the twins, i remember an old man in the big electric city and one of the gym leaders is your father and i don't know anything else. at least in gen 4 i can remember volkner, roark, crash waker and glacia. and rowan >>>> birch everyday.