Hey there! Congrats on your admissions! You must be an exceptional student to have been accepted at both of these amazing institutions. I have done extensive research on both of these colleges through personal visits, reading their websites in depth and by reading any and all opinions I could find online. My disclaimer for this comment is that Middlebury was my first choice, applied ED1 and was denied. Bates was my second, applied ED2 and was accepted. With that being said, I’ll be attending Bates in the fall and looking back over my experiences with both, I’m glad for it.
Academics and sports at both of these institutions rock. You didn’t need me to tell you that, but my point is that no matter which one you choose, you have little chance of choosing wrong in that department. Of course each has their own specialties (Bates has been known in the past for its tendency to graduate"teachers and preachers," and it’s recent addition of a computer and data based department and Middlebury places a special emphasis on its language and environmental programs) but mostly I feel like they’ll easily be comparable. I have a sense that the workload at Middlebury is a touch heavier however that’s just from what others have written.
Bates was much more comfortable to me that Middlebury. I felt like Middlebury had a more competitive air to it. It just struck me as preppy and exclusive both times I visited, where as the people at Bates set me more at ease. I went up to a random table full of people at Bates and they happily answered my questions for about 10 minutes. Not to say anyone was unfriendly at Middlebury, but that’s just how I felt.
The food was much better at Bates in my opinion (and with one mostly centrally located dining hall, it felt a bit more homey).
Middlebury had a more appealing campus for me however. I just really loved the wide open space, the stone buildings and the gorgeous Vermont landscape. Bates is also really pretty, though I think anything compared to Middlebury’s campus will have a hard time matching up. It was also really big which I think would be troublesome in the winter time.
Middlebury had nicer library and science facilities. Town is a short walk away. At Bates, lewiston is honestly up to your own opinion, but I think I’m going to appreciate it’s diversity and wealth of opportunities that I know I couldn’t have found in a place as rural as Middlebury. Bates also has a bigger emphasis on purposeful work and community engagement. Middlebury seems to have done more with sustainability, but everything I have read about Bate’s sustainability programs have made me absolutely giddy for next year.
Overall, I think where I am at athletically and academically (18/377 students, public school) Bates is much more my style. If I had been accepted to Middlebury, I know I would have felt like I was constantly trying to be “good enough.” Of course as an accepted student, I’m sure you fit in better there than I would have 
I just think you need to take a moment, put the stats and rankings aside, and ask yourself where you think you’ll thrive, both as a person and as a student. That was hard for me to do. If I had done that better and evaluated myself better, I would have figured out that Bates was for me much sooner. I wish you the best of luck!