I would rather go with the i5-3317u. The base clockspeed is 1.7GHz which is 100MHz lower than the i3-3217u. However, when Turbo Boost kicks in the CPU can go up to 2.6GHz if only one core is being used and probably 2.4GHz if both cores are used. That can be a significant difference in performance especially in the future since everything generally becomes more CPU intensive.
It will be much more easier to replace the HDD with a SSD in the future, than it would be to upgrade the CPU because the CPU is soldered into the motherboard which basically makes an upgrade impossible.
The i5 will treat you better in Photoshop during editing, but it's still a limited CPU since it's the ultra low voltage type. The SSD will make a bigger splash when it comes to saving + loading large projects, as well as installing/uninstalling programs.
I suppose a good question would be: how big is the SSD? If you need more storage space than it offers, then get the i5 + HDD.