A grade is a grade, a rank is a rank, percentages are a proven method

This.

I like a 5-point scale, and it was my original choice. However, I must say I'm becoming increasingly infatuated with the idea of a 2-point scale (thumbs up/thumbs down) as an absolute statement of opinion (rather than an absolute statement of quality).

That doesn't even make sense! There can't bee an "error" in a scoring system, because that implies that you think something that isn't in the score!

YOU
CANNOT
BE
SERIOUS

 is giving a game 4 out of 5 the same as giving it a PRECISE score of 80%, no its not , and its logical

Precision in scoring is bad. It's not logical unless we accept the idea that there is an objective scale of quality to be considered.

There isn't.

 Precision = accuracy............ bottom line_________________

ie, i was here at this precise and accurate time.

There is no objective scale of quality for video games. Trying to be "precise" is at best pedantic and at worst stifling concerning dialogue as to what makes a game good.

Dailogue with a percentage at the end satisfies me more than any A+/B- or 5/5 could ever do

What satisfies you is not what constitutes a proper scoring system.

So what exactly is the best scoring/grading system?