Don't go for the S5; Touchwiz is crap.
Get a OnePlus One if you can. I have one and boy it is a beauty.It is $350 with 64GB of space, 3GB of ram, Snapdragon 801 2.5Ghz processor,and a 13MP camera if you like those.
that phone has terrible issues, screen yellowing, reports of numerous bugs that haven't been fixed backing breaking etc
i love my s3 so i can't really speak for the s5, just don't get the 4.
just got the s3 and love it even though its old. and my battery is bad so I ordered a replacement