Samsung Galaxy III vs iPhone 4s?

I'm trying to decide to either getting the Samsung Galaxy III or the iPhone 4s. I'm wondering which one is better or that you enjoyed/preferred.
Thanks in advance!

Added (1). Thank you both for the very helpful answers! I really appreciated it. But who to choose for Best Answer? I would choose you both! BUT Thanks a million times!

I've had both and can honestly say the s3 is better i don't go with apple whatsoever anymore they basically re-release products with new names double the price. The s3 has a nice big bright screen more free apps and cheaper ones too. If you like watching youtube in HD the big screen is amazing for it. If you like playing with the specs you can find custom roms on xdadevelopers.com and change the whole look and feel of the phone. And can go into any and all folders on the s3. Apple make you pay for that. And if you still want to change your look on the s3 you can download some from the built in playstore for free with no technical difficulties.

So in my opinion get the s3

EDIT: you could always go onto youtube and watch some reviews. I always do that when getting expensive things

The 4s is now an outdated phone. The processor is slow in comparison and it runs off of 3g speeds. The Galaxy S 3 is hands down the better phone. If it was the iPhone 5 vs the S3 I would tell you it's personal opinion because they're both on the same level.

I have the S3 and I love it. I work with selling phones and everyone of my Co workers have the S3 and love it too, my boss has both the iPhone and the S3 and he prefers the S3 greatly. It's super customizable, has a beautiful display, the processor is wicked, and it has expandable memory. People come into my work all the time to exchange their iPhones for S3's, it happens the other way around too but not nearly as often.

The galaxy phones are cheaper and faster but easier to break. Samsung invented bendable material so in the future maybe the galaxy S4 will be unbreakable. I would suggest waiting till then because both Samsung and Apple are working on a new model that will make the 3 and 4s absolute