It depends where you're going, how far and how many punctures you think you're going to get.
Goop seems to get the thumbs down from everyone. Not sure why - I've never tried it.
Grant's the expert, so I shall merely try to anticipate his reply! He's done years on tubed tyres but has decided to go tubeless for safety reasons - i.e. when he gets a puncture on a cliff edge he wants the tyre to deflate nice and slow...
Other arguments are:
1) regular-sized punctures are dead easy to fix if you have tubeless tyres - a 5 minute job with practice. Big splits or gashes are another matter - you may have to fit a tube as an emergency measure to get going again. A real pig of a job.
2) Tyres are harder to change with tubeless tyres because you have to break the bead, which may require special tools.
3) The best off road tyre is, according to the aficionados, the Michelin Desert. It also has the virtue of being practically puncture-proof. But it's only available in tubed form. Tubeless off-roaders have to make do with the Conti TKC 80, which is the next best thing.
4) tubeless tyres last longer 'cos they run cooler
But most people's choice is probably determined by the bike they've already got, and their budget. If your bike has spoked wheels, and it's not a recent BMW, then you've probably got tubed tyres, and going tubeless means buying new wheels. Have you not got an off-road bike yet?
P.S. Sounds like you haven't read Chris Scott's Adventure Motorcycling Handbook, which covers this topic very well, plus a zillion other vital things. Go to www.adventure-motorcycling.com.
If a thing is worth doing, it\'s worth doing to extremes.