Effect of Forces on Gantry Cross-Sections?

[WandrinAndy]

I'm having some difficulty getting to grips with lateral resistance and torsional forces and deflection, particularly on a Y-axis gantry of about 800mm unsupported, so am hoping that a discussion comparing the coloured cross-section pics I've attached will help me and probably others too.

Only now that I've drawn these up and can picture them properly, I think the varying degrees of ease-of-construction, alignment, ease-of-changing-pulleys, etc., are fairly self evident from the pictures, and know that the impact of the respective weights on acceleration needs to be considered, but the gist of my confusion is around rigidity and stiffness.

GREEN -- 45x90 ------- 3.9kg/m extrusion
PURPLE - 120x60x4 ---- 3.7kg/m rectangular tube
BLUE --- 152x51x6.35 - 6.5kg/m rectangular tube
RED ---- 152x51x9.53 - 4.9kg/m angle + 45x45 extrusion 1.9kg/m

If cost were to be ignored for now, how do these cross-sections compare to one another in terms of resisting the forces experienced during cutting aluminium?

Thanks,