I have the Euromesh seat on my Giro26.  I have a pair of standard-design aluminum bottle cages mounted.  The problem is, one of them is not real secure, even when bent up tight.  The bottle tends to pop out under road vibration and either be lost on the road, or grind itself badly on the rear wheel.  Those nice insulated bottles are too expensive to keep having to replace them, too.  Part of the problem seems to be that with the Euromesh laid back, the bottles are a lot more horizontal than the cage is designed for.
 
I am wanting recommendations on a better bottle cage.  I run them left and right on the back of the Euromesh.  I have looked at the Specialized side entry "Z" cage for $$, but it would not work on the left side.  I am also looking at the Kleen Kanteen cage designed for 27oz bottles (it's taller/longer than a regular short cage), and has 2 circular bands around it to hold the bottle in place.  Anyone else have any recommendations?  The bottles I use are 24-27oz insulated Polar and Podium bottles.  ( I also run a 100oz bladder in the brain box).  But I like the bottles for mixing gatorade in.

I'm looking at the Arundel Sport (plastic and cost effective for me) currently.  Gee, I could even get yellow ones, and have them match my bike!  The DaveO cages look nice but are WAAAAY outta my price range.

I've had good luck with various historical versions of the specialized cages
 
http://www.specialized.com/us/en/ftb/waterbottles-cages/cages/ribcageroad-mtb

The Specialized cages come for either side; I have a left-side one on the Formula.  I would recommend Trek's old "Bat Cage," but I don't think it's available any more.  It's the best cheap cage I've ever used.  Mike L. sells a heavy aluminum sideways one at Easy Street that doesn't bend so much.  It says Origin 8 on it.  I have it on my Musashi.