which guitar better for early Beatles sound?

If you are trying to emulate the parts George played, then the Gretsch is the one to use. If you are trying to emulate the parts John played, then a Rickenbacker is the guitar of choice.

There are a lot of videos on YouTube of people playing Beatles stuff, and IMO those criteria above match best..

If you are looking to achieve a similar sound you should:

a. Try out various guitars

b. Remember that the combo is what achieves the effect ultimately the amp and any effects.

I read in one of my Fender books that George played a Strat, even though that wasn't his primary guitar. You could consider it?

Harrison hated the gretch he had....well docmented...in the studio he did a lot of his early recordings using fender / vox combos...most often strats...there is one that he actually had painted... there is a you tube video / interview where he states exactly that...

strat will likely be your choice, gl