People averaging 50+ during the 1990s (20 Test minimum): Tendulkar, Waugh, Lara, Gooch.
People averaging 50+ during the 2000s (20 Test minimum): Flower, Yousuf, Ponting, Kallis, Imzamam, Hussey, Sangakkara, Jayawardene, Tilakaratne, Gambhir, Lara, Chanderpaul, Dravid, Thorpe, Waugh, Hayden, Tendulkar, Younis, Samarweera, Pietersen, Graeme Smigh, Virender Sehwag.
People can decide for themselves, and I've been given a few reasons for this. Sorry, I don't buy any of them so far. To me, it has been patently easier to score runs. 4 people vs. 22 people. Sorry, personally, I can't rate those runs the same way.
Obviously, people have their own ideas, and they are welcome to them. Not for me though.