Depends on what you're using it for. For applications that utilize more CPU cores, the I5 is the better option. For applications that require more memory (dealing with larger files), then the I3 is the better option. Since this is a laptop and over-clocking likely isn't an option, I'd probably go with the Core I5 and later upgrade the RAM to 8GB.
Hello main priorities are
Super super fast boot times quick sharp responsive.
Super fast multi tasking
10+ chrome tabs mainly news websites or blogs but of YouTube and office.
No No gaming at all. Only solitaire