Asking a community college professor for a letter of recommendation
This is hard to weigh without knowing more information about you, but it can be addressed in a general way.

One of the biggest pieces of advice I give to undergrads is to develop a relationship with professors they hope to earn letters of recommendation from, including going out of their way to take extra classes/do extra work with them.  Now that that ship has sailed for you, I would lean toward the community college professor.

You don't mention the other letter you got from your BA institution, but I presume it's a solid one.  That allows you a little more leeway on your second letter.  You can already show strong results at the BA level, so getting a very good letter from a community college professor (or, e.g., an employer from the private sector in your field) that knows you well will look better than the generic letter.  People who read these letters know what a generic letter looks like, and are certainly able to "read between the lines" and assume this letter doesn't say much good about you.

I would be concerned if none of your letters came from your BA institution, so if my assumption isn't correct about the other letter, then I would say you probably have to use the generic one.