You have to be in a certain mood if you are going to watch a certain movie out of the OT rather than another one, the same holds exactly true for the Indiana Jones trilogy.
If I am in the mood for seeing how it all began or want the most fully realized story out of the bunch, I'll watch ANH or ROTLA
If I am in the mood for the darker, more serious film of them all, I'll watch ESB or TOD.
If I am in a happy-go-lucky mood and I want something fun and upbeat that day or just want to watch a true popcorn flick, I'll watch TLC or ROTJ.
As for the one I've seen more out of either trilogy, I'd have to say that I have seen ESB and TLC the most.
