I concur with Elaine. My personal opinion has been that females in general tend to make better pets (this opinion has been formed by various pets I've had over the years), but after reading Elaine's post I think she's right, but of course it also depends on the pet's individual personality.
My wife and I have two girls that are less than six months old (they're about six weeks apart in age). We got Coco six weeks later than Gracie. Coco's a lovey-dove, whereas Gracie is more "independent", or shall I say,
SHE decides when she wants hugs and kisses.
The potty training does take time and patience (with a couple of small children I would imagine even more so). Our two still aren't 100% reliable; I wish that one would learn
GOOD habits from the other, but I'm afraid the reverse is true.
Gracie & Coco scrap, and at first it concerned us a little, I realized they're establishing dominance, but sometimes it sounded a little ugly, they're terriers, no blood no foul. You'll find posts on here regarding what to do for that (basically just keep an eye on them).
We didn't go male & female simply because of the marking/going into heat dynamic.
In short, everyone has an opinion, but we love our Gracie and Coco so much it hurts. I would recommend that whatever you decide, take your time, and make sure you let your two prospective pups spend some quality time together to test for compatibility before you make your final decision. Good luck to you and your family.