What type of buttercream do you like best?
Mine would have to be italian meringue buttercream. Even though I've only made it a few times, its by far my favorite. I love the texture and the flavor. Its not as fast as a simple buttercream, but its well worth the time spent making it.
Mine is IMBC too, although on larger cakes I usually stick with ganache. I find the IMBC method is quicker & easier than other buttercreams. I do tweak my recipe a bit to make it a little less 'buttery'.