This is in the Gazebo, so I'm not sure why the thread is mostly about videogames.
I'll discuss tabletop only. My answer to the original poster is "depends on what you ask".
The 1990s was the best decade for a RPG gamer to enjoy the hobby, because you could enjoy all the incredible stuff released in the 80s, and add a few cool things from the early 90s. But while the 80s was an explosion in creativity with dozens of amazing games, very different rulesets and rich, original settings, the 90s is the decade where everything went to shit and most games died.
The "hot decade" was roughly between 1983 and 1993. The rise of MtG in 93 disrupted tabletop forever, and while still some good stuff was released, it was mostly inertia, since the creative teams did not stop releasing overnight. Nearly every system declined sharply.
Let's break down game by game, at least the ones I know/played:
Rolemaster and MERP: clearly the best years were 1983-1990. MERP in 84 did well, and they had some lovely Middle Earth stuff released in the few following years, but then they started with the filler. ICE was in a sorry state after 1990.
D&D: In 1983 TSR released Mentzer's BECMI, by 1989 AD&D 2e, 1991 Rules Cyclopedia. That is, they had two succesful (and amazing) games in active development. After 1995 the Basic branch was pretty much dead, and AD&D2e was releasing a weak revision of the same rules. About the settings, have a look at the dates. Greyhawk (80), Mystara (81), Ravenloft (83), Dragonlance (84), Lankhmar (85), Forgotten realms (87), Spelljammer (89), Dark Sun (91), Al-Quadim (92) and Planescape in 94. But by 1996 they had pretty much killed all of them, with the exception of Forgotten Realms (Planescape still released stuff in 1996, and probably there were other exceptions). Real sad.
WFRP: my favorite RPG, released in 1986. Some of the best adventures ever released for any RPG were released between 1986 and 1989 (Lichemaster, Shadows over Bogenhafen, Death on the Reik). By 1990 Games Workshop abandoned it and licensed a couple publishers during the 90s (Flame first, Hogshead next), which weren't terrible, but didn't manage to release anything noteworthy, nor released enough content to keep the game truly alive.
Vampire the Masquerade: A solid game released in 1991, but by 1993 it had already released all its best material (Chicago By Night, Ashes to Ashes, Milwaukee by Night, Mummy, Hunters Hunted) and were already releasing loads of useless junk such as the clanbooks, and worse.
Runequest: I don't know it as well as the ones above, but from my understanding, the good editions were the Chaosium ones, up to 1984, then they had huge trouble in 94 with Avalon's editions and pretty much died for several years.
Cyberpunk: golden years are 1990-1994, pretty much collapsed after that. Like everyone else.
Shadowrun: another one I don't know that well, but this one might be the best case for the 90s, since it's where the most popular editions were released.
Call of Cthuluh: Chaosium released its best editions through the 80s, and all its incredible supplements as well, with the exception of Horror on the Orient Express in 91.
I am probably forgetting many others I played, but I think I made my point.
The 80s took a hobby in its infancy, and turned it into a multitude of complex and rich games/settings for us to enjoy. Creativity was off the charts. And not just the books, just look at the magazines, to see how alive RPGs were. It was an age of wonders.
The 90s found gaming in its peak, and at first did well, but quickly began declining in quality and originality, and by the end of the decade it was almost dead as an industry. Wizards of the Coast took the pieces.