A lot of great responses! We went through this same discussion with my 2016 last year.
I agree with what MidAtlantic says. Every coach at every school is looking to bring in better talent every year. There are zero playing time guarantees anywhere IMHO.
My boys wanted commitment from the coaching staffs for Spring roster spots in year one. And (ideally) a four year roster spot commitment to the player if he was working hard on and off the field and there are no disciplinary issues. Playing time then is 100% on the player outperforming the other guys. And the roster management become pretty self selecting...guys leave the team who aren't playing and pursue other things (internships, travel abroad, intra-murals, tougher majors, etc.).
Many coaches will not give the above commitment. My 2016 had a dozen D3's that would. And he punted from his list any that would not, i.e., those that had annual tryouts, those that would only "guarantee" fall roster spots.
If you have the four year baseball commitment from the coaching staff (presuming they stay around!) then the selection of what college to choose comes down to everything else: majors and minors, academic support, weather, campus aesthetics, size of the student body, location, dining options, workout facilities, baseball field and facilities, etc.
Our perceptions of what the coaching staff brings to the table is important too. Do they develop baseball skills? How is summer team placement? Competing for post season play then became one of these factors. It's important to most players and definitely was to my boys.