I'll tell you what I use, and why.
As a head, I use either an Acoustic Image Clarus or Focus, the latest series of each before they went to the Clarus +.
I tried other bass heads, but those preamps inside were geared more to adjusting bass frequencies, and the Acoustic Image heads can be used with guitars, keyboards or bass (with less sound options for bass compared to other heads).
For cabs, I tried a few, but went with 3 different Schroeder cabs. I have the light mini 10, light mini 12 (both with the bullet tweeters), and a custom 15+L.
In the 15+L, Jorg replaced the bullet tweeter with a Selenium horn, which has a wider throw than his stock tweeter and hits those highest frequencies. All 3 cabs are loud and clean.
I never use any of them together, I take just what I'll need depending on the size of the room. Both the 10 and 12 sound better from the front rather than from the side (where you might be setup) because of the narrow long throw of the bullet tweeter, so you don't hear it as good as someone standing 10 feet in front of it. My 15 sounds good from the side because the Selenium horn throws wider. My 15+L cab is also an inch bigger all around to fit the slightly bigger horn, so the bass might be slightly deeper, and the cab weighs less than a standard 15+L by a few pounds because the Selenium horn weighs a few pounds less than Jorg's heavy bullet tweeter.
I play Kurzweil synths exclusively, and this setup works for me.