just my own opinion but the OEM sport drop with 19"s may leave you wanting more drop. I think 18" with OEM sport sits nice and clean. Aggressive wheels or 19"s need more drop.
The ride ht is not affected by the wheel size. That is because the OD of the tire, not the wheel, stays close to the same.
Another way to look at it is, as the wheel size goes up the aspect ratio of the tire goes down. The sidewall ht goes down... 45, 35, 30, 25 all of them are percetage figures. They do not have units of measure, just a percentage.
Aspect ratio is a percentage of sidewall ht divide by the tire's cross sectional width all in millimeters You get numbers like 40, 35, 30 and even 25. They are the aspect ratios.