I love Gunnar glasses and own two pair, amber lens and clear lens. If you only want to buy one pair I recommend clear lens. Both amber and clear reduce my eyestrain and headaches during long screen sessions but, if you ever use for applications were color accuracy is important, i.e. digital art, video or photo editing, etc. the amber lenses alter color perception. I learned the hard way because my first pair were amber lenses and I had to get the clear pair for apps requiring accurate color mixing/rendition. Hope my experience will help a first time buyer.
I use this one daily. Being a programmer am staring at the screen all day, and colors are not important to me. This has seen many falls and pushed around, especially with a toddler around, and has held up really well, so I got another one of these.