For me no doubt someone else's hand is far more erotic. Just the way you described it with your wife is so hot.No one gives me a better handjob than me since I feel everything. But the touch of someone else's hand is also magic. So it just turns a little differently.
I've never had a handjob from a guy, unfortunately. I used to assume guys will do a better job because of experience but watching masturbation videos I see there are a lot of different techniques being used and it seems to me there is quite a difference between people with cut and uncut cocks.
One of the best handjobs I was given was by my wife. We sat on the couch, I started caressing her breasts a bit with my arm around her and then below her arm, she rubbed my cock over my pants. Then she opened my pants and started jerking me off. She'd never done that like that, I mean nearly clothed, not in bed, not without foreplay. The feeling of her amazing breast in one hand and her hands on my cock in that situation was amazing, even though it took a bit more effort on my side. Sadly it never happened again that way.
I have many a handjobs done this way fully clothed on couches with various girlfriends and must add one of my favourite way after a good session making out and often spontaneously.
I fondly remember a few times where a couple of ex girlfriends were more than enthusiastic