While I don't use it for longer trips, I find that I rely on my Esbit for 6-7 day trips. Knowing I can rely on solid fuel and counting exactly how much I will use in advance makes the Esbit a sure bet for me.

I used a penny stove for ~2 years exclusively, as did my hiking companions. Knowing we could share fuel in a pinch was nice, and the at-home tinkering and testing was certainly fun to while away the time.