Sounds like you're very happy with GK... I'd probably just be looking at a GK Legacy head and either the CX series or Neo IV series cabs in whatever configs make you happy.
That Neo IV 212 cab looks pretty sweet. 800w, 44 lbs, $900. Pretty good. I just paid hundreds more for a less-powerful Aguilar SL212, but I wanted the Aggie to match my Tone Hammer 500 head.
Though a little pricier, I also really like the Mesa Subway series. I have the TT800 head and 115 and 210 cabs. They are simply fantastic. No matter what combination of bass or amp I'm using, they just deliver in spectacular fashion. Clear, authoritative, effortless power with those babies. Read around here on the forum about the Subway 115. It is probably the best balanced all-in-one cab for small to medium gigs. It is not AT ALL like you would think a single 15" cab sounds like. Yes, slammin' lows for days but also beautiful and clear mids that just shouldn't be possible with a giant speaker like that. After decades of being an Ampeg user, the first time I hooked up the Subway 115 was truly a revelation. It was like every speaker cab I had used before was under a thick blanket or something.... Imagine having lived 40 years with moderately poor eyesight, then one day you finally get glasses - you see everything with a new clarity and refinement! Images come to life and things "pop" into view... that's what happens with your ears the first time you use a Subway 115, haha!
I see you're in Nashville. I'm just 20 minutes down I-24 from you. If you want to try out some Mesa and Aguilar gear to see what you think, holler.