I prefer the finish line dry as I find the wax un the cam lube actually gunks up my cams. My HB quad cams used to actually advise using finish line dry in the instructions.
WC advise to use WD40, but IMO its not a very good lubricant and it attracts more dirt than finish line dry.
On the plus side WD40 has been tested with climbing gear and it doesn't harm it. Finish line dry has been tested I'm sure by many climbers but I'm not aware of any scientific tests. I try and keep it away from my textile gear until its fully dried.
In reply to Blue Straggler: I would say it is worth cleaning and drying the cams every few years prior to lubing, but most times I don't bother (or need to), just wipeing off the excess finish line dry does actually clean the cams to some extent.
I would always use some lube after cleaning and rinsing the cams for optimum performance whatever.
Perhaps a silicone or teflon spray lube? The former dries completely so wont attract dirt while the latter (bike chain spray) partially dries and leaves a teflon film. Not used either for that purpose though.
Screwfix do a Teflon aerosol. It's dry lube so doesn't attract cack, fantastic for cams and trigger groups in rifles, locks and switch gear. It's much cheaper than the 'specialist' sprays and works just as well. That said, I've never had a problem with WD - except once and it resulted with me getting stung by a lot of wasps
Bicycle chain lubes. The drier varieties are better as they won't pick up grit. Something like Pedros Ice Wax or Boeshield T9 work well. T9 comes in a both a drip bottle and a spraycan and lasts for absolutely ages on cams.