I've had a reasonably close look at MEC's bikes in the past when I have visited the US. I've liked what I have seen.
To me, the bike linked to on craigslist looks pretty good. Sora is not exactly a high level Shimano groupset, but it's durable enough. The bonus is that it has the disc brakes, rack and fenders. The bare bike is listed currently on MEC's website at just over $1,000. See if you can negotiate with the CL seller.
Incidentally, ensure the bike fits you. It doesn't matter how good a bike might be and the equipment on it, you won't enjoy riding it if it doesn't fit you.