B, most likely. Colleague recommendations, unless they are SPECIFICALLY asked for (like in the Stanford app) tend to be very weak. The reason is that they aren't your boss, so they don't oversee your work, and whatever goodness they would write would be less effective then when it comes from on top. If he is willing to help, then you can easily make up for his con of not being all that involved, by reminding him a wee bit of some of your achievements etc. Very important, which you haven't really mentioned yet is that your recommender be EXCITED! So try and think about that too.
If you like the post, give it a KUDOS!