I really like the propane/butane stoves for one main reason.  I'm lazy.  I don't like fiddling with anything after hiking all day, I just want to open my backpack and start cooking.  I remmber using the white gas stoves when I was in the scouts, they were nice, but too much fuss for me.  They also only have two settings, off and blowtorch 

.  I'm guessing the Simmerlite has solved that problem, or it would be a really misleading name.  
Right now i have a Snowpeak Gigapower, but it's about as simple as you can get.  Screw onto fuel container and turn the knob. You can have adjust the flame anywhere from simmer to burning a hole in your pot. No priming, no pumping, no hoses to connect or stands to setup, no nozzles to clean, etc.  You don't even need a lighter, it's got a piezo start built in (highly recommended).  If you live in CA and don't have to worry about low temps, look into a vapor fuel stove, they're really convienent.  One drawback for a propane/butane stove is you can't check the fuel level in the container.  I don't really have a problem with it, if in doubt I carry an extra cannister, it's still lighter than a bottle of white gas.  Also, supposedly they fuel isn't as readily available in foreign countries, but I've never checked if that's the case.