Both are great for premed and will have excellent premed advising. Both have high acceptance rates to med school, largely because of that premed advising.
Full disclosure, my D is a Bates grad. Their grad school advising is fantastic all around, as is their scholarship advising. She loved the location in Lewiston. Not a glamorous city, but it offered enough to do, with plenty of places for food and shopping. When they wanted more, Portland was nearby. The close proximity of the airport in Portland was convenient. You child can read this excellent thread for a better idea of what to expect from both Lewiston and Bates. The Horrible Misconception about Lewiston
My D was a very studious kid and while she did party, she didn’t party hard. It wasn’t her scene. My D didn’t didn’t apply to Colby as she felt the slightly more laidback and collaborative vibe of Bates suited her better. Most people here would say Bates is a bit more liberal than Colby, but it’s not like there are hippie flower children and regular demonstrations on campus. There are a ton of kids at Bates who applied to Colby, and vice versa.
Bates’ language program is small, but excellent. My D studied a completely new language at Bates and ended up doing so well with it that she won a couple of awards for her language achievement.
I’m personally not a fan of first year college students starting their college careers abroad. I know kids who have done this (not at Colby), and while some have had good experiences, most didn’t get the experience they hoped for. It was a dramatic adjustment to kids fresh out of high school. Some felt it put them at a disadvantage when they finally arrived on campus. It also made it hard to decide if junior year study abroad was a good idea.
She should try to attend accepted students’ days at both. She is going to have a wonderful time at either school, but these schools have so much in common that it’s probably best to go with the atmosphere she prefers, barring a big difference in FA.