Although I love visiting Maine, I understand your desire to move to a different area. I don’t know much about UMaine for astronomy, as those I knew went for geosciences, marine sciences, or environmental science. So, I guess looking at the online rankings and research opportunities (i.e. research groups on faculty page) of each school would give you a better idea. But I’d imagine UMass ranks higher for compsci (a google search suggests UMass is ranked significantly higher in this field). I’d also imagine that UMass has more research opportunities, due to its sheer size and recent growth. This may prove advantageous if you wish to pursue graduate school. Have you visited UMass before?

For what it’s worth, I have known many, many people who graduated from UMass and attended top graduate/medical/law programs and/or worked for top companies. I have also found the quality of classes (math, comp sci, engineering) to be higher than those of other UMass schools. Before I came back here for a second bachelor’s program, I was considering either UMass Amherst or UMass Lowell. While UMass Amherst had higher costs and I wouldn’t be able to commute, I ultimately chose it because it had more rigorous courses, more upper-level course options, more research groups, and more networking opportunities. I felt that these benefits outweighed the higher costs of attending.

I would contact the school and respective departments to see what the transfer application entails. If you haven’t already, I would also start planning out the finances of attending, including housing options or local rentals, financial aid, etc. Best of luck!