1.)Bright & on Avg last a lifetime of a car & color from White - Blue - Purple to chose = HID/projector lighting but that also = a bit of $$$$ as well as time (Catz can save to big bucks if considering this) !!
2.)Still bright & not usually last very long and not usually recommanded & still can choose your color & Risk to melt your wire and housing LoL = 80W+ bulb = why would you do that ? hehe
3.)As long as it is brighter than stock & change them approx every year & still can chose your color from yellow to purple = PIAA/Silverstar/After market ricer bulb

/9006-9005 etc = that's what i use to have, happy with it hehe
4.)As long as i can see at night & change them when they burn out (3-4 yrs +) & yellowish white is your fav color & rather spend the $$$ to get a CAI or something = stock = most economic lol