There's practically no difference and you can custom rom them anyway. Samsung's stock ROM does have some features that are others are not allowed to have (eg split screen). The S4 will be cheaper too, the korean S4 is octocore too, so that's nice.
People are going nuts over chinaphones like alcatel or xiaomi or huawei now days. Personally I like the huawei phones like the honor 6, it's about the same price as an S5 or One M7 but it's octocore, 3gb ram, etc, basically much better than what korean or jap brands are putting out IMO.
Nokia is always good too.