tennisplayer1993
Professional
The 90s had:
Sampras
Agassi
Becker still a huge force in the early to mid 90s
Edberg in the early 90s
Courier a huge force in the early to mid 90s
Ivanisevic a monsterous presence on grass and carpet, would have won multiple Wimbledons in virtually any other era
Muster and Bruguera both clay court demons, plus Kuerten in late 90s another
Rafter a huge force at the end of the decade
Then you have a supporting cast of guys like Chang, Stich, Krajicek, Kafelnikov, Moya in the late 90s, Rios in the late 90s.
You metion Martin and Pioline. Guys like Martin, Pioline, and Medvedev, (who nearly won the FO in 99 past his prime of the early to mid 90s), Philipoussis in the late 90s, Henman in the late 90s, were all either multiple slam finalists or frequent top tenners who nearly won a slam, and yet they are barely in the top 20 most important players of the decade behind all those I mentioned. That is depth.
It was an exciting decade to say the least. I started watching tennis in the 2000s because of age. The people I know who have followed tennis since the early 1980s, adored the 1990s because it was so hard to chose slam winners at each event making it more fun to predict who will win which.