I just looked up the games with a MetaScore of 85 or above for the last 10 years and made some charts of it:
Without the "generation-model", the PC platform has a nice selection of good games each year, but even there were some slow years (2006 + 2010).
The transition from Xbox to 360 went impressively smooth... over 20 great games for the first Xbox in 2005 and even 6 in 2006, then the support died. At the same time, the Xbox360 had a solid launch with 4 good games and 10 in the following year.
The PS2 had only 10 games with a MetaScore over 85 in the launch year of the PS3, but good PS2-games were released up to 2009. The only high scored PS3-game at launch was Resistance, 13 titles in the following year.
The GameCube support died before the release of the Wii: Twilight Princess was the only high scored game for GC + Wii in 2006, the year before only the great Resident Evil 4, Fire Emblem and 4 sport games.
In the year of the Wii U launch, Xenoblade Chronicles and La-Mulana were the only high scored Wii games, but 5 third party WiiU-games reached the "85". The year before 3 Wii games: Skyward Sword, Rayman Origins and Tiger Woods 12.
PS3 and Xbox360 had still good support in the launch year of their successors, but the only high scored launch games for PS4 and XBO were some sport games and download titles.
