What is the circumstance you are in where you cannot tutor for tinker but can play Transmute? The only one I can actually think of that is realistic to think could happen is Meddling Mage, but mage can just as easily name Transmute if they wanted to. Things that prevent you from going into your deck like Aven Mindcensor affect all these cards equally.
If you have a tutor in hand and your options are tinker or transmute, in what situation would you pick transmute in the course of a normal magic game?
I'll put this another way. I would sooner run my first copy of personal tutor than my first of transmute in almost every situation I can come up with, and that card sees no play.