I you can only afford Aqueous, the similarly priced SR will give you more bang for the buck. However, if you can afford a little more (for the Venustas) you will have the best cable value in audio IMO.
I was considering SR, Transparent, and Straightwire Virtuoso, when I wandered into the Purist room one year at CES. I'd never heard of Purist and thought they were demoing a terrific sounding speaker (Eben) until informed they made cable ;-) Back home, I'd been trying to make a decision on a new expensive tonearm cable, when I spied the fattest TA cable I'd ever seen (a Venustas) on Jim Aud's (Purist's owner) TT at the show, and wound up buying it ("it's already broken in" he said!) I paid $650 (less than half of retail) and when I got it home, I totally freaked out! Subsequently I recabled my whole system with Venustas.
The one thing Purist does better than anybody (and everyone who uses them will agree) is low noise floor. No cable has a blacker background (and that includes Siltech and Stereovox) As far as tonal balance goes, it is of course system dependent. But I have a neutral and articulate system (electostats, driven by tubes, of course ;-) and the Purist cabling (including power cords) has maintained that system neutrality for me, while revealing more detail and stable image. Their speaker cables have very low capacitance, which is important for driving most speakers but particularly for electrostats.
Synergistic, and even more so, Transparent, have a bit more, oh, I guess you'd call it "sparkle" (and with my system, I don't need any more of that! but you might ;-) however you will pay for it with some background hash (which you'll never notice, unless you A-B them against Purist cables.) I'm quite sure this is due to Purist's outstanding (if somewhat bulky) mechanical shielding (Ferox).
Whatever you decide, at this level of 'sophisticated cable design' I'd recommend you stick with the same make and model of cable throughout your system.