All excellent academically and have strong reputations. That being said, they are a bit different culturally in terms of student focus and campus vibe.
So please take these as grand generalizations but within it is some directional truth. Imho.
Skidmore is arguably one of the most passionate “student activist” type cultures in the USA. It’s part of the attraction for many students. It would hold the opposite appeal for others.
Colby is a pretty remote location. Gorgeous and socially active. It also can be more oriented around the “weekend festivities” than others due to the location.
Bates is probably a bit of both. It’s also a very strong brand in banking and finance in the northeast USA.
If I had to choose one based on your specific observations. I would choose Bates. Location. Portland and Boston. Access to airports. Outdoorsy. Diverse politically within reason.
Academically it’s a wash to me. Bates and Colby tends to be viewed as slightly more selective in my region. Skidmore is also considered very selective.