In R/B/Y and G/S/C, I got Blue and Silver first cuz I just liked them better. It didn't really matter to me the order in which the games were said. Well, it didn't really matter to me, becuz I didn't think too much about it back then! Then i broke the tradition(without even realizing it), and bought Ruby and FR when they came out, just cuz I like the colors better. I'm getting Diamond first tho, not becuz of the way the name sounds, but becuz I like Diaruga LOT, and Mime Jr. is exclusive to Diamond. My bro is getting Pearl, so everything is fine. But I'll be getting a Pearl for myself, so yeah...
Anyways, I'm POSITIVE that Diamond will be favored over Pearl.