Gen I - Green. Sassy son of a... Gen II - Extra region was cool, but didn't like it being fairly empty. Gen III - Lack of features introduced in GSC (see: best Generation). Gen IV - Like Hoenn before it, the region was largely unmemorable. Gen V - Unmemorable Gym Leaders. Gen VI - <1% of the trainers have a full team of six Pokemon.
Gen 1: Charizard Gen 2: Kanto Gen 3: Lack of Electric types Gen 4: Slow and kinda bland Gen 5: stats for certain pokemon and evo's that don't make sense Gen 6: Lack of 1 eeveelution, not enough new mons and too easy