Neither. My wife always prefers her huge dildo, because that allows me to be in my proper place licking her while she is enjoying a "real cock." It focuses all of my attention and all of my abilities on pleasing her, allowing me to work the dildo as she pleases and also use my tongue and fingers to stimulate her clit and anus. She has also told me that she stopped enjoying the strapon we used to use because she did not like either of us pretending I am a real man who can properly fuck.
My Wife still prefers a strap-on on me. But i hope that soon She will abandon me in the role of an active partner, capable of performing frictions and will stop putting a strap on me. And She will finally close me in chastity. I will try to do everything to make it happen as soon as possible.
We have used both, and the best options, in our opinion, were Vixskin models. We stopped using the extension because a) it meant that I had to be unlocked, and b) once I was in it, it was a little large for Mrs Edge, and I had to be very careful about using it. She decided that she prefers me to wear one in the harness because a) no unlocking, and b) she likes the feel of the cage bumping into her.
Strapon of course. She abandon and tossed out all but one sleeve. The only one she has kept is the black mamba xl. When I am locked, it is to a specific date so the strapon is the method we use. If I am free and about, we may try on the black mamba for a little fun before I get my turn at her. Otherwise, if she wants size it can always slip onto one of the dildos on her strapon.