Adding 4% to the overall price, for a ~10% faster CPU. Both are viable options.
By the way, you don't need a Z77 or Z87 motherboard or watercooling for these CPUs - they can only be overclocked a little bit. If you want overclocking, you should get a Core i5-3570K or 4670K.
So you'd suggest the 4670? Would I really notice the difference?
And I agree, water cooling is a bit much, but the Intel RTS2011LC Liquid-Cooling Kit is really cheap right now (57% off its $100 price tag). What motherboard would you recommend for no overclocking?