Experimenting with matting or no matting

I recently had a portfolio review with Emily Schiffer thanks to Photograph Resource Center Boston and she along with others suggested doing my photoziacs without matting.  She offered up the print option of Metal or Wood; as soon as our meeting was over I jumped online knowing my custom print lab offered up metal prints.  I decided to Experiment with my image called Green.  Below you will see side by side comparison of the same size frame but two very different looks as one image are printed on metal and the other is on foam core and matted. 

Please leave a comment and tell me which one you like and why?  I love reading your comments about my art!  I’m working on another comparison one in my Infrared series- so stay tuned.