It depends on what is most important to you.
The Prius hybrid will get you the best overall mileage and reliability, but I think the Civic looks better.
The Insight will be a little less expensive than either as a base model, but I, personally think that the Prius is still a better vehicle.
Overall, I would recommend the Prius right now. The new 2010's are coming out with even better mileage and you can get a pretty substantial discount on the 2009's while the price of gas is still relatively low.
I have a 2007 Prius, package #2 and have had no issues, to date.
I average 50 mpg in the summer and 44 mpg in the winter.