Well getmyownarcade seems to be the most talked about arcade script the URL is http://www.getmyownarcade.com/ i think
How do you define as 'best' ? I think it is really subjective here and what works for others may not work for you. Guess you should do the evaluation yourself and see which meets your needs.
Currently, I think the best one (as far features go) is Advanced Arcade Script. It's very easy to modify stuff and support is excellent. I bought the script recently and like it very much. My 2c