How could you say that "The Library" and "The Revenge" episodes are funnier and better than "The Massuse", "The Lip Reader", "The Heart Attack", "The Limo", "The Parking Space", "The Pick", "The Opera", "The Bubble Boy", "The Handicap Spot", "The Pie", "The Chaperone", "The Race", The Label Maker", "The Mom and Pop Store", "The Scofflaw"? The episodes I mention above are much funnier than the two old, crusty episodes you mention in your top ten best. Think about it.
My list certainly leaves off some very good episodes, namely the ones you mentioned. I suppose in a classical sense, all in all (writing, acting, plot) , the episodes you named are better than "The Library" and "The Revenge". However, these two episodes rank highly as my "favorites" for different reasons. I don't think I've ever laughed harder than when Kramer tried to put the cement in the washing machine. And the "library detective" character absolutely cracked me up. Also, the flashbacks to Jerry and George's teenage days were hilarious. Though "old" and "crusty", these shows are excellent examples of what got Seinfeld the critical acclaim (and the fan base) that it enjoys now.
By the way, when I made my top ten list, I listed my 19 favorite episodes and trimmed it down. In my top 19 were "The Masseuse", "The Lip Reader" and "The Limo". There are 11 episodes I haven't seen - among them "The Race" and "The Mom and Pop Store".