Especially when you add in the playoffs, of course it's last season. Paul didn't have the individual numbers, but his defense, leadership, and all-around game was at its peak, and statistically, his offensive efficiency was at an all-time high (career marks in eFG% and TS%).
2005-06 was an amazing season, though. Pierce set career highs in points (26.8 ), free throws attempted (10.7) and made (7.9), and field goal percentage (47.1%), with his second best year for assists (4.7) and third best for rebounds (6.9). He scored 30+ points in 13 out of 14 games in a late season stretch, which, if you remember it, was easily the most amazing stretch of his career; he was hitting clutch shot after clutch shot, and of course there was that epic 50 point game against Lebron. In terms of individual play, Pierce has never been better, and that includes this year's playoffs.