2005/2006: Ovi had 4 more points, 13 more goals. Easily the better player that season. More impressive =/= better. (Just like how Selanne was not the best player in the league in his rookie season, despite having one of the most impressive rookie seasons ever). And if anything, Ovechkin was just as impressive (if not more): 3rd in rookie goals and 3rd in rookie points in NHL history (2nd place for both were in a much higher scoring 80's, and only 1 goal and 3 points ahead of Ovi)
2006/2007: Crosby easily the better player. No debate here
2007/2008: Ovi had Ross/Hart/Pearson/Rocket, 13 more goals than #2. Better points/gp than Crosby, despite actually playing the whole season. Ovechkin's goals/gp was 75% higher than Crosbys. Ovechkin had a good playoffs (still only had 2 less goals than Crosby despite playing 1/3 as much). The fact that Crosby's team performed better does not clear the edge that Ovechkin had in the RS, and the fact that he played just as good in the playoffs too. Team success =/= better player that year.
2008/2009: Ovi had Rocket/Pearson/Hart, 7 more points than Crosby (higher point/gp too), 23 more goals than Crosby. Ovi lead the league in points/gp and goals/gp. Ovechkin finished T-4th in goals and 5th in points in the playoffs (despite only playing 2 rounds). He actually had a much better points/gp and goals/gp than Crosby did (enough so that if he were to have played more rounds, it's likely that although his /gp stats would have likely decreased a bit, he potentially could have finished with more goals and equal/more points). Again, Crosby's team success does not make up for the huge gap Ovi had in the RS.
2009/2010: Tied Crosby in points and only had 1 less goal, despite playing 9 less games. Wins the Pearson, and finished ahead of Crosby in Hart voting. point/gp and goal/gp lead. 12% higher point/gp and 10% higher goals/gp than Crosby. Both had great performances in the playoffs, despite losing in 1st/2nd round. Crosby had 0.03 points/gp higher, Ovechkin had over 50% better goals/gp, but let's call them even in the playoffs, Ovechkin was clearly better in the RS.
4/5 = 80%. The only possible argument for the last 3 seasons is by a crazy overvaluation of the playoff raw totals (because in reality Ovechkin played just as good in the playoffs - just no team success) that Crosby had due to the Penguins success, and using that to try and make up the clear gap that Ovechkin had in the RS where he swept the Pearsons and goal/gp and point/gp leads, as well with finishing with higher Hart performances in all 3 as well.