I liked the sound of the inline 4 in my 2002 quite a bit, but in general SQ goes up if the engine is described as 'flat' - e.g. a flat 6, or a flat crank in a V-8 or V-12.
A flat-6 is horizontally opposed cylinders not a crankshaft layout (and isn't a flat crank btw), and is naturally mechanically balanced whereas a flat crank V-8 is a method of getting more power (but higher vibration) from a V-8 layout.
AFAIK there has never been a flat crank V12 since both a straight 6 and V12 are both perfectly balanced and even firing without, the crank pins are at 120/60 degrees, like the flat-6.
Mass market V-8 normally has the crank pins at 90 degrees to get mechanical balance but that results in uneven firing, giving the classic burble but less power than the same engine would have with a flat plane crank.
Sporting V-8s thave a flat plane crank and don't burble (though of course there are loads of high capacity tuned V-8s with plenty of power that burble, they can only be taken so far though) for ultimate performance a flat plane crank has to be used to both even the firing and make proper exhaust tuning possible without pipes crossing over from one bank to the other. The price paid is that secondary out of balance is inherent in a 90 degree V8 with even firing layout (and all 4-cylinder engines too fwiw).
I am not sure how manufacturers deal with this. Very few production cars with V8 engines have a flat plane crank just because of harshness and vibration.
It needs 2 balancer shafts running at 2x engine speed to correct the vibration. Balancer shafts can make a 4-cylinder smooth too, like the Porsche 944 enigine.
Basically only straight 6, flat-6 and V12 layouts are inherently "good" from both a mechanical and thermodynamic pov but are not the easiest to package, or cheapest to make, so guess what? there aren't many about!