If it were me, I would buy the bike that I liked the best, and then include that in a supplemental insurance policy if it's going to be locked up in a public area pretty often. That way, if you've found the perfect bike, you can ride it every day and not worry so much.

I don't really have to worry about this, as my work parking is very secure (much more secure than home, actually), so I ride the nice one to work and back, and I take my inexpensive bike pretty much everywhere else.