The decision between the Galaxy S5 G900F and Galaxy S5 G900H is a tricky one from a number of perspectives. However, theres one category of buyers that can completely discount the Exynos model from the word go: if you want LTE, the G900H isnt for you.
If youre indifferent about LTE support, or your carrier/location doesnt have LTE, there are other things to consider. First of all, general CPU performance from both the Snapdragon and Exynos models is fantastic, with the Exynos model having a slight performance advantage of around 5%.
During general use you wont notice any difference between them, which is a testament to the quality of both SoCs.
When it comes to graphics, the Snapdragon 801 blows away the Exynos 5422 by an average margin of 67%. Despite the large difference its hard to notice when actually playing a range of 3D-intense titles available on the Google Play Store, and thats mostly due to games not requiring all the power of a top-end SoC. Grand Theft Auto: San Andreas is one game that you can notice a sizable performance advantage to the Snapdragon model, but its the only time I noticed the performance gap.
Of course two years into the future its hard to know if the GPU power of the Snapdragon 801 will be needed to play the newest Android games. If you want to be absolutely sure you have the most powerful chip going around, grab the G900F, but for the next year or so (at the very least) the G900H will suit you fine.
The battery life gap has been closed between the Snapdragon and Exynos SoCs as well, with the Snapdragon chip pulling head only marginally across most of the tests I performed. Again, the Snapdragon-powered G900F does have an advantage here, but in actual use the difference will be minimal.
The main reason to purchase the G900H over the G900F is its price. The Exynos-powered G900H, unlocked and off-contact, will set you back $600; while the Snapdragon-powered G900F is available for $650. If you want the cheapest Galaxy S5 and dont care about LTE, there is no reason to look past the G900H.
With previous Galaxy devices the Snapdragon model had a clear advantage in all key areas, but with the Galaxy S5 the Exynos model is finally good enough and close enough to the Snapdragon model to recommend. Samsung still has a bit of work to get their Exynos SoCs completely on par with Qualcomm, but were now closer than ever.