Price wise....I think the Mesa has more value even now when everyone and their momma is buying wallet sized amps that weight 12 ounces.
I have not owned the Mesa, but a friend does and I jam on his now and then. It's a good amp and does the Mesa tone well, but you can also dial in some cool vibes with it. I don't have any extensive time with the F1 to tell you how they compare. Judging by what others say about the F1, I think you will find the Mesa more gooey sounding, but similar in how dark they both are. At this point, I would have to say the Mesa is more flexible tone wise.
Are you going to be using the Markbass 210 cab?
-Mike