If you've got the option, I'd go with an opposite sex. I've had less problems with female/female than male/male relations - it really depends so much on the dogs themselves and how dominant they are. I too would highly recommend not breeding. There are too many things that can go wrong and too many sad stories from people (myself included) who ended up with heartache from poorly bred dogs. My last beloved Pyr (rescued) died very young of autoimmune problems and one before that we put to sleep because he was so dangerously, uncontrollably aggressive even toward myself and my kids (got him as a pup). Personally, I am a huge supporter of rescued dogs. If you go to the working dog forum you can read some posts on my new LGDs, Katie and Carter. I was very specific with the rescue groups as to what I wanted and came up with two GEMS! That said, I also turned down a few that I just didn't feel comfortable about. The more research you do before you get another dog, the happier you will be in the long run. This forum is a great place to start!