So now that you are reading this, do you know what the best guitar is? The truth is that there is no BEST guitar. You might buy one from an extremely reputable company that SAYS that it is the best, but its not. Truth of the matter is The Best Guitar In The World is your favorite one.
My favorite electric is my black 1979 Gibson Marauder. It is positively the sweetest freaking beast there is. It has been played so much that the upper fretboard is almost scalloped (Scalloped fret guitars have grooves in the upper fretboard that make picking not necessary).
My favorite acoustic is my Countess (off name brand) that I got in Korea. It resonates so well and I only payed 0 for it. That is about one eighth of the money I have spent on acoustics and it plays better than all of them.
That being said there are a few things a beginner or anyone with little experience wants to look out for when on the hunt of the best guitar in the world.
First thing I do is touch the strings and press down. What I look for is very little space between my strings and my fretboard. This can make it very uncomfortable to play and it shows poor craftsmanship.
Be wary though of too little space, if you find one that feels good pick it up and play every note on every string. You don't have to pick them, sliding will work just fine but make sure you hit every note. What you are checking for is fret buzz. Fret buzz happens when you hit one note and the string comes into contact with a fret higher up on the fretboard. Say if you hit a note on the seventh fret and the string hit the thirteenth fret it would buzz and that would be fret buzz. *Disclaimer* When strings get old they will Naturally create this problem, do not be alarmed unless this is happening with New strings.
The next thing to check for on you search for the best guitar is the word is simple. Outward flaws. Pick up the guitar and stare straight down the fretboard. Make SURE that sucker isn't crooked. a crooked neck can spell all sorts of bad news for a guitar. If its a new guitar check the outside for dings and scratches, just to help you out on getting a better price.
With that, hopefully you know, but haggling is ok. Everyone does it, and every salesperson will do it, even if they try to play it off like they don't. I got my dad a 00 Electric Yahama for 0 just by talking to the salesman and reasoning with him. Don't ever take the first price.
Once you do all that then Bam! You have got yourself a potential best guitar in the world. All you have to do now is take it home and rock out brother. Then in a couple of months, you can start the search for your Next best guitar in the world!