Re: Custom built cabs. What to look for?
Thanks guys! I'll try and help you troubleshoot a bit:
Genre of music: Hard rock, heavy sounds mostly. I won't be droptuning to minus Zb, use 9 strings or need absolute tightness in terms of tone. I'm
not looking for an Animals as Leaders/Strapping Young Lad sort of thing.
My tonal preferences are more modern Marshall than say the 5150/6505/Triple Rec setup.
More Mastodon/Down/80s Metallica/90s Megadeth than Dream Theater. I like mids.

I think I'd prefer a 2x12 over a 1x12 just because, man. More is more and I want more. But not too much. Tiny apartment with no storage unit which is why a 4x12 is out of the question.
Current setup: My trusty Egnater Tweaker 15, which for home usage and ocassional jamming/gigging is OK.
When I upgrade, I'll keep it around the 20-50W range which is why I dig efficient speakers (more on that later on)
Guitar wise, high output passive pickups into something Gibson/PRS-esque usually does it for me.
Usage: Mostly at home, but I will start gigging out which is why I like the Emi Wizards; they're so easy to dial in a band and it's crazy efficient so 15 watts have been enough more than once.
Also I've used my Wizard for so long that I'm just at home with them, they're crazy flexible with good EQ and can easily do 70s classic rock sound one minute and death metal the next.
Recording is not a big priority.
Regarding home usage, I'll keep my open back 1x12 cab and will probably load it with the most unefficient speaker I can find that sounds good, to keep things quiet and tasty at the same time.
Your suggestions have been terrific and I'm keeping note of all of them. Thanks a lot guys!