As others have said, the best i5 on the LGA 1150 socket is the i5-4690K. It's the newest, and also the most powerful in specs.
Since it's so new, however, it's recommended you get a Z97 or H97 motherboard for it if you're building a new PC. The older Z87, H87, B85, or H81 boards require a Bios update to recognize the new CPUs, which is impossible unless you already have another older CPU installed.