Which is best among these 3 camera?

Nikon s3000 vs. SONY W310 vs. Canon a3100is.

Nikon

Sony all tha Way

Nikon

Canon a3100is.

but you should go into the store and hold and play with all three. They are all good and it's really just preference

and also make sure you read the amazon.com rating;
the sony isn't rated as great.

Sony

Nikon s3000 is best.

Nikon 3000 is the best

No doubt frinend, its NIKON