Consider a custom loop, will be more expandable than any AIO in the market, XSPC makes some. Swiftech H320 is another option, Water 3.0 ultimate is for something really big.
Do you prefer water or air cooling? The corsair hydro series are great water coolers. The Noctua NH-D15 is a fantastic Air cooler but is quite large and the looks don't appeal too everyone.