I considered a 21 inch wheel with a 3.9 sidewall height. That pretty much would be the same diameter as factory 20 inch wheels with tires. But then again, with a tune and h&r lowering springs, the ride will be a bit more stiffer, plus a fraction of traction might be lost.
Currently on h&r, without much seat time, but i do like the 4.3 inch sidewall, factory 20 inch height, as it acts as cushion to bumpy roads. Also, these cars seem a bit big, therefore, larger tire sidewall suit them good IMO.