Alloy Water Bottle Cage

This one, is one for the classicists; timeless styling that works on nearly all bikes (but perhaps not an all-out aero rig), combined with timeless, corrosion resistant titanium gives you an option that you'll probably have to leave in your will to the grandkids. 

Tall slots, rather than holes, give an additional degree of up/down adjustability to really fine-tune the position too, which may be of particular benefit to those on smaller frames.