Every 'solution' has it's pros and cons... it's up to the individual to decide what works best for him/her.
I'm not a fan of foam inner tubes. Sure they're not subject to flats but then they don't ride like pneumatic tires either.

Puncture resistant tubes are OK and seem to offer decent protection but they can also be a bear to install and add quite a bit of weight and rolling resistance.

Self sealing tubes... I don't bother with them because they can really create a mess... not a big deal if you pay someone else to deal with it but I don't so IMHO they're not worth the hassle.

My solution to flat prevention relies on getting good tires... to me the function of a tube is to merely make an air-tight seal between rim and tire... a well designed tire should handle all other necessary aspects of ride quality and duraility. As Juha mentioned, Schwalbe Marathons (like the HS 420) is a great tire and has an integral 3mm belt to help protect against flats. Some Kenda Kwests also incorporate similar flat prevention measures (known as 'K-Guard'). I've also been impressed with Conti Gatorskins... there are plenty of tire options available in order to negate the chances of getting flats.

However the best solution to preventing flats is to be aware of and stay clear of potential flat hazards.