Another possibility is the Pelican M6.

All-metal body, a bit longer than a Surefire G2. Has HA2 (sted HA3) body anodizing, so it will show wear and nicks quicker than comparably-sized Surefire light. However, it's still sturdy - just dropped one of mine off a porch railing onto concrete driveway about 12 feet or so below. Got small nicks on it, but the lamp lit right up again. Pelican also has a very good returns policy for their lights.

About the same price as the G2, especially with some of the vendors on CPF.
Throws (I'm told) a bit farther than the G2. Lamp assemblies are about $7 each vs. the Surefire assembly prices.

Also has the option of making the tail a clickie instead of press for momentary on, twist for constant on. CPF vendor flashlightlens.com sells the mechanism, which apparently takes a bit of elbow grease to install (I bought my Pelicans used, with the clickies already installed).

I think the Pelican's a good-value light, very much a contender to the Surefire G2.

Dave