Either an i5-4690 / i7-4790/k now or a Skylake later should easily give you 3+ years. Personally, if I were you, if you can hold out wait for Skylake CPUs to be released to see how much better they benchmark and what the cost differential will be. Also note that if you plan to overclock, it's being said that the first Skylake CPUs will not have a K series and won't until sometime in 2016, so also something to consider.