Here are the facts: the honda insight is 5 grand cheaper than a prius and 4 grand cheaper than a civic hybrid. It get 10 mpg less than the prius but the same mpg as the civic hybrid. both the prius and the civic are more poweful than the insight. Safety wise and reliability wise both Hondas are the same. Toyota has been getting a bit lazy and while its probably just as safe id say its not quite as good as Honda in terms of reliability.
Personally Im not a fan of hybrids because they don't make financial sense. the technology is just not there yet to make the extra cost worth while. buying a normal cheap light weight car is better for your wallet than buying a new hybrid. but if you have your heart set on a new hybrid at the lowest price you can get then go for the insight. The mpg difference between insight/civic and the prius is not big enough to warrant the extra $5000 for the prius. I wont run through all the math but in short it would take you 2000 fill ups in the prius before you would start to see a savings over the insight. Assuming you drive about 15,000 miles a year it would take you 71 years to do that.
Having said that if you are looking for a hybrid with a bit more luxury go for the civic hybrid. the prius does have more luxury's available but it costs over 3K more than the top of the line civic hybrid.
Is this going to be your one and only vehicle or is it just for commuting? If its just for commuting get the original insight if you want to be environmentally conscious. It get about 50-75 mpg + it'll cost you half as much to buy as the entry level 2010 insight.
I hope this helps.