I totally understand if the Shiva isn't your thing. Wasn't mine either when I had one in my studio for a tryout. I respected what it did, but the tone wasn't quite what I had in mind.
Here's what I like about a single channel amp for the kind of music you're doing:
A two channel amp has a clean channel designed to be clean, and a gain channel designed to be dirty, but it's hard to live in that sweet spot for blues and rock where you're able to get the goods between clean and dirty simply with your picking hand, without even touching the volume controls on guitar or amp.
In my humble opinion, only a single channel amp will let you live and thrive there.
I have a Mesa Lone Star that's designed for the kind of music you're talking about, but even it will not give up the goods in a truly organic way like my single channel PRS amps.
For the kind of music you like to do, the HXDA is (for my taste) THE amp. Period, bar none, best ever, etc., etc. I do like those plexi style tones, and as much as I like other PRS amps, and other non-PRS amps, it's been #1 in my life ever since I first put one in my studio.
If you're more of a Tweed guy, there's the DG30, something I think of as more of a roots music amp in my own use of it; the amp has a hauntingly beautiful tone, especially at lower gain, and at higher gain settings breaks up really nicely, but in a different way from the HXDA. The DG also seems to need more volume to really shine than the HXDA.
With the HXDA, I have the amp set up so that by setting the guitar volume to 5 or below, I get gorgeous, shimmery clean tones; above 5, the tone gets thicker, and by 6-7 is purring along nicely. At full guitar volume I'm in RAWK territory.
The only two channel amp I've had that could come close to this kind of responsiveness was a Two-Rock Onyx, an amp that's been out of production for quite a while. I've had some of their other amps, but the Onyx gave me that rock-blues thing with great touch sensitivity to a greater degree than their other models.
So that's the two of the three PRS amps that are currently made that are single channel. I'd love to try a DG50, which sounds like kind of a cross between the DG and HXDA in clips, but I haven't been able to play through one yet.
Of course, there are any number of choices on the used market, but I've never really been excited about buying an amp without a warranty.