Regardless of which car you buy, be advised that ALL of them undergo sorting issues that are usually resolved after a few thousand miles. If you are building the car yourself, there are things you can do that will help with that problem, but there are always unexpected surprises.
All of them have outstanding performance. The power to weight ratio is terrific. The Type IV engines and the subaru engines offer great power and reliability. If you are truly insane you can go with a 6-cylinder porsche engine or a TURBO subaru both of which are cabable of changing zip codes immediately! Most of the suspensions are somewhat crude but offer surprisingly good grip particuliarly on smooth pavement.
Safety is an intersting question. I had a fellow at Knott's last year very concerned about "safety". He wanted a "safe" car. "Safe" means the absence of risk. No deal on these cars. They are small, light and open. You crash, you lose. Someone talking on the cell phone runs over you, you lose. Suggestions: LOUD horns, drive with your lights on all the time, keep it in gear at stop lights (to make a quick move) and drive like everyone is out to get you. If you can get a fuel cell for the front then do! Carry an extinguisher just in case.
See the cars in person and drive them. Each of us has our favorite and you will need to choose yours. Another good option is to buy a slightly used one that has already had a few thousand miles to "shake out" the new car teething problems.
hope that helps
angela