My first reaction was to keep the Leupold. I have owned both. I still have a nikon that I keep for use on the shooting range. BUT in all reality they both leave a lot to be desired. I love leupold and nikon has come a long way, but when it comes to spotting scopes you have to spend the long dollar. All my rifle scopes are leupold but binocs and spotter swarovski/zeiss. If your really into hunting and seeing things far away, sell them both and get the one you will have forever and probably sell for what you paid for it. They are a pretty decent investment. I have the swarovski 20-60, but I'm selling mine and buying a 20-60x80mm HD. Good glass makes a world of difference.
If I had the choice between the two I'd go leupold. Good luck.