1: http://www.guitarfriendly.net/images/chords/diagrams/g-major-chord.jpg

2: http://www.play-acoustic-guitar.com/images/GMaj-Free-Guitar-Chord-Chart.png

I'd really like to know which is best to use?

There's a LOT more than 2 of 'em.

Those are in "open position". Which means some strings are "open" or unfingered.

And there is no "best" version.

You just use the one you like the sound of the most ?

To understand this better, you'll need to understand some theory.

You can't go wrong here:
http://justinguitar.com/en/CH-000-Chords.php

The G-major chord has the notes G B and D.

Now, the difference between the two chord shapes you posted, is that in the first you play a D on the B-string (3rd fret, fifth string) and in the second example, the open B is played (open fifth string).

Essentially it is the same chord, because both the D and the B are part of the overall G-major chord shape. Which one to use will depend on the song you're playing, but harmonically it should not matter that much.

There are many more chord shapes for the G-major:

24 G-major shapes

As long as you're playing a G, B and D, it will be a G-major.

See all possible positions of G, B and D on the guitar neck, to come up with your own chord shape:
All G-major notes on guitar

Hi, as has been echoed correctly in this board, depends on what sound you want as both variations ultimately are a construction of the G major chord (g,b,d).

If one wanted to get technical you could say that the variation with the d note instead of open b string is more 'harmonically stable' due to the harmonic tendencies that prefer to double the root or fifth instead of the third in root position chords (as applied in writing 4 part harmony voices, whereas first inversion tends to be more flexible) i.e. the g is the first, b the third, d fifth (regarding intervals). So the tendency is not to double the third, but besides such trivial technicality it boils down to your preferred sonority; we by certainly shouldn't be straightjacketed by rules ?

So... learn both and other voicings for your own development and just predominantly use the ones you like, good luck ?

synju wrote: 1: http://www.guitarfriendly.net/images/chords/diagrams/g-major-chord.jpg

that one!

Yip, as mentioned earlier, I also prefer the one synju indicated, good old G major such a pleasant chord ?

Can also choose based on the chord progression. I find G to D easier with the first. But C to G easier with the second. I imagine you don't need these simplication techniques once you get a little more skilled

I find it's best to learn all chords in as many different positions as possible, and then use them when needs be.
Sometimes you have the luxury of being able to play the chord in your favourite position, sometimes you need to play the chord in the position that allows you transition in time...and some times you need only play a part of the chord, or only the triad on your 1st, 2nd and 3rd string.

For myself, my favourite G I like to play an open G, but fret the d on the 2nd string and the B on the 5th string. It's a big, fat G for strumming, and offers lots of option for finger picking. the obvious being to lift the D to a B on the B string to switch between voicings.