You said he is on prozac. Has his behaviors gotten better or worse with it? Some dogs become more reactive. Have you worked with a trainer? Crate, food, toy and other guarding behaviors are not an "easy" fix, but most certainly can be changed.
BRAT (Basenji Rescue and Transportation) will list mixes, so that is one option.
He was adopted from a shelter (born there). The vet started him on Prozac like 8 months ago or so. We think it helped him slightly, but the unpredictable behaviors are not changed. We have had some luck with positive reinforcement surrounding the crate and food and he's good 90% of the time, but the other 10% of the time he can just snap. We definitely aren't blaming the breed, either one. We just wanted somewhere to reach out where people understood basenjis and some of their quirks. We plan to try behavior training but it is likely the last thing we can do. Ultimately, we are scared of the unpredictability and fear that when we have children they won't be safe around him.
@kfpolen - If that is the case (born in a shelter), then you will never know his real story..... The 10% of the time that he "just" snaps.... could be a sign of rage syndrome. Meaning that it is possible that there are "wires" crossed in the brain... Since he was born/raised in a shelter, have you asked the shelter if they can shed any light on his behavior
I don't really see any Basenji, Corgi for sure, I see
It's difficult to give you advice on some of the behavior issues without actually being there. And the aggression part can take some time to overcome but a really good trainer can help.
You could contact the Certified Professional Dog Trainer Association (http://www.ccpdt.org/dog-owners/certified-dog-trainer-directory/) to find a trainer to help.
You might also try the Pembroke Welsh Corgi society (http://www.pwcca.org) to find a breeder in your area who could recommend a trainer (roundabout way of getting some help).