I have owned a Bogner Shiva 1x12 (not the smaller cube), a Blackheart 1x12 (with a new speaker), a Lopo Signature 1x12, an Avatar Vintage 1x12, and an Avatar Traditional "Wide" 1x12.
The Shiva cab was awesome but I highly recommend the Avatar Wide 1x12. It is oversized, yet still very portable. Rear loaded and has insane low end for a 1x12 cab. I plan on ordering a 2nd one in a week or so. Sounds awesome with my Blackstar and PRRI. The Avatar Vintage 1x12 was a little boomy and hollow sounding in comparison.
FWIW, at first I thought the Blackheart sounded really good. But that was with a Greenback Heritage speaker at really low volumes. Every other speaker I tried in there made the cab sound real small/boxy. It does sound good at bedroom volumes but really falls apart at louder volumes. The Avatar Wide cab holds up really well.