My favorite of all cabinets I've used, and unfortunately no longer have, was a Mesa Boogie 2x12 that had a fully closed-backed bottom section and open-backed slant top section. I had a JBL D-120f in the top and a Electrovoice EV12M in the bottom. It was an incredibly well balanced cab and sounded great with all of my amps. Today I use an assortment of combos and Fender cabs. I'm in the process of opening the back of one of my closed-back 1x12s to use along with one of my other closed-back 1x12s, both loaded with JBLs to find that balance again. Due to physics, closed-back cabs have a nice tight, well defined bottom, and open-backed cabs a better high-mid, and high end in addition to the ambience and dispersed sound. The bottom end of open-backed cabs is loose, and weak in comparison to that of closed-back cabs.