Both, equally, for me. A good play or musical has the power to move audiences while entertaining them. What I especially enjoy is the unexpected and having to think a bit with a theatrical experience.
It really depends on the season. This past season I really got into the off-bway play In & of Itself (saw it a few times) and the bway plays Angels in America, Harry Potter, The Children, Iceman Cometh, Boys in the Band. The only musicals I got really excited for were the revivals of My Fair Lady, Carousel, and OOTI.
Musicals were my first love and I've seen far more of them than plays. Having said that, I've loved probably 90 percent of the plays I've chosen to see on and off Broadway. And this season, this calendar year, really, I've seen more plays than musicals. Today's obscene prices force me to pick and choose more carefully, and there have been so many worthy plays. The Ferryman was magnificent. This weekend, thanks to the two-fer Friday, I'm seeing American Son, To Kill a Mockingbird and Network. Normally at least one show on a trip up from DC would be a musical; this time I'll have to count on the holiday markets to break up the intensity of what I'm seeing on stage.