It's hard isn't it?
I spend way too much time on petfinder personally, and I had probably 4 dogs in mind when I managed to convince my husband to get another. I was accepted for the first one, but didn't have the opportunity of meeting him. I said ok anyway, as I knew I could bring him back if there was a problem... I have no regret at all.
It's funny, because when I met him the first time he was really shy, didn't want me to pick him up, and had his tail between his legs. Well he had spent 2 weeks in a shelter, and just spent 5 hours in the car coming up from Virginia, so I knew it didn't mean much... I picked him up anyway, he was really skinny, and lighter than my already small cat. He wasn't really at ease, but we took him on the grass a bit... After a few minutes he started licking my face, even though he was still shy.
Well now he comes to me with his tail wagging all the time, gives me lots of kisses, and is so far extremely easy to train. He came to my brother in law with his tail wagging too, I can't wait for him to have all his shots so I can really start socializing him more... He's sleeping against my feet as I'm typing.
Bottom line, i think all dogs are wonderful when you get to know them... So it's so hard to have to choose.
Oh and I agree, that lab mix is really adorable.