I choose it based on demand for a review of that unit (generally as I see it), or interest in historical versions of that unit. Additionally, for new items, I gauge demand based on whether the unique is simply ‘damn cool’.
As a geek of sorts, if something is awesome, I’ll likely review it (even if not mainstream). If it’s clunky, out of date, and not worth half the cost, I likely won’t bother. I’ve only got so many hours in the day, and I prefer to spend my time writing about really cool stuff, rather than just ‘blah’ stuff.
As I’m sure you’ve said leaving a boring meeting before “That’s x hours of my life I won’t get back” – it’s the same thing with my reviews. Since they often take upwards of 20+ hours to put together, I don’t want to say “That’s 20 hours of my life I won’t get back”.
Like most folks – I like playing with cool stuff. Sound good?