I think most people choose males if they are looking for just a single display animal. Males are most often the most colorful of the two sexes and make better display animals. They also tend to live longer.
Rarely do experienced hobbyists obtain only a single female for display purposes, unless of course they have hopes of eventually finding male for pairing later down the road.
Most hobbyists get a pair for the obvious reason of trying their hand at breeding.
Since you already have a male pardalis and are considering another pardalis, ask yourself if you simply want another display animal or if you want to try your hand at breeding.
If you do get another chameleon, regardless of sex, you will need another enclosure.
For me, I like female chameleons best. They tend to have more character and although their markings may be somewhat subdued, they are quite beautiful in a more subtle way.
The only issue with females that may be considered challenging is their egg production. But , they certainly give enough indication to allow for a prepared egg laying site. It shouldn't present an overwhelming problem for someone with a little experience.