I like the look of both of them. At the moment, i'm leaning towards the mountain bike since it looks more durable. Also, I took my Dad's hybrid out for a ride today and the handlebars felt really low. Mountain bikes, on the other hand, have high handlebars which means less wrist pain and general hunchiness!
Also, you may have been helping with my previous thread on deciding what type of bike to get. A lot of great ideas were bounced around, and they really helped me focus on what I wanted. A big thanks to everyone who posted (especially big chainring).