Being a mid-tower, the interior space for bulky liquid cooling components is limited. To make it work nicely, you'll have to be specific about which system or LCS components you choose. The best solution for a pump and reservoir is a 5.25 drive bay mounted one, such as this XSPC one. With two of the larger components neatly tucked away in the ample 5.25 inch bays, the only other bulk you need to worry about is in the form of a radiator.
What's nice about the RC 690 is that you can mount a radiator just about anywhere: on the side panel internally, on the side panel externally, on the back internally or externally, or on the top internally.
So there you have it: An inexpensive, non-space-hogging, liquid cooling friendly case, brought to you by Cooler Master.