For me, two biggest positives for the Mach E over the Y are the $7500 federal tax credit and the better service availability.
I never thought I'd need much service on my 3, but unfortunately I have. I have a "lite" service center one hour away and a "real" service center five hours away. Mobile service was available when I bought my 3 but Tesla then took mobile away in my area. That coupled with my trouble getting service (non roadside assistance) on the phone is starting me to re-think the model Y. I love Tesla and like the app for making service appointments, but sometimes I need to actually speak to someone. For example, my front passenger window was stuck half way down and I determined I needed the window regulator assembly (I was correct). The app was going to have me wait 2 weeks and drive 5 hours away only to find out the part was not available. I had to do some crazy hacking to actually speak with someone. Tesla service should be better. For those owners that have no service issues, that's great , I had hoped to be one of those owners too.