If it were up to me, I'd rather it be the San Antonio Spurs that advance out of the Western Conference this season. The Spurs admittedly have the advantage of never having lost an NBA Finals series, however that doesn't mean that they would be unbeatable in this year's NBA Finals.
If the Boston Celtics make it out of the East then they would instantly have the chance to improve upon the team's record of 17 championships won in 21 Finals appearances.
The Lakers have been to the finals 31 times but have only won 16 Banners, barely 50% (that's less than Shaquille O'Neal's fg% this season)! As for which Finals matchup would be tougher for the Boston Celtics, well, we'd have to actually get there first, however as history (or recent history) has proved neither one of those teams is unbeatable. The Los Angeles Lakers are our main rivals though, so there is always that aspect to look at. I cannot wait for June 2011 to come so that I can watch the Boston Celtics in the playoffs...