I would think painted do look better and last longer, but....
I currently have the 'Rally Racing' stripes. I really don't like them because I want them to extend further down the hood and wrap around the spoiler.
For this reason, I just purchased a set of 'bumblebee' vinyl stripes on ebay for around $150.
I just need to have them installed, and hopefully it will be around $100 for install.
The reason I am not painting them on is because I might 'repaint' the entire car some time in the future ( 3+ years) and so I don't want to waste my money. I do, however, want that great look that the stripes give it, now.
thanks,
BL.