[cairo] OT (slightly) - which surface should an application use?

[John Ellson]

Given cairo's abilities to render to various different window
surfaces: xlib, glitz, xcb, sdl, egl, ...
its possible for a single application to be capable of  working with all 
of them.

How should an application choose?     Is there a complete-ordering of 
quality
or performance such that one is always preferable over the others if it 
is available?
Or should the choice always be left to the user?

If the choice could be automatic, can anyone point me to some example code
for evaluating the choice on a system at run time and settling on a 
particular surface type?

John