If we are rating a set by the amount of keywords, Betrayers of Kamigawa was a good set.
Onslaught was a set filled with boring medium-range creatures with dull flavor (hurr durr beasts are awesome
), overpowered small beats (Goblins are a stock fantasy race so they must be good right, right?) and horribly underpowered-could-be-cool Wizards and the ever-so-dull Elves (even worse in Legions/Scourge where they're birch twigs on legs). It managed to botch the race matters theme by adding really good creature sweep (Slice and Dice goes in almost every red multiplayer deck I make), reusable kill (Slide/Rift) and big win-more finishers (Visara).
The best sets I've played with are Ravnica/Guildpact/Dissention and Invasion/Planeshift/Scourge booster drafts, but the current T2 metagame is probably the most varied in years and I probably would play some if I had money for $200+ playsets of lands.
Lorwyn looks like a big pile, especially limited and even though I like the flavor of the set I am not going to buy any packs, even for limited. They really are pushing control though, which is my favorite archetype after land destruction/burn decks.
Also keywords are a good thing. After the initial learning threshold they are easy to remember.
edit: Also almost half of those keywords are used on less than five cards, and even more are rubbish abilities that noone uses anyway (lol Epic)
edit edit: :wtc: why is landwalk an important keyword? Flying or trample are more important as keyworded abilities, as they are interactable evasion abilities. Landwalk is lame and that's why it isn't printed anymore (exept maybe some base set stuff?)