I understand there are more Galaxy's sold Vs. the iPhone.
I have an iPhone 4 and considering the 5 or Galaxy 4s?
Apple's releasing the new 5s soon so if you're considering the 5 you should wait a bit and get the 5s or a 5 for a reduced price.
but as an android user I'm gonna suggest getting the 4s. rooting an android device makes it waaaay better. you can overclock your android. but if you're not into that the stock galaxy 4s still functions great out of the box. the galaxy's gonna seem a lot larger but you can get used to it.
How about the One?
Don't overlook the size differences also. A big reason I did not get an iphone (got I9300 instead) was it was too small. I am 6'6" and my thumb covered up half the screen.
You might consider GS3 I9300 as well. Easy to hack, Wolfson DAC and cheaper now that GS4 has arrived.
I put some opinion in here: http://www.head-fi.org/t/661448/us-samsung-galaxy-s4#post_9405152