Most of mine are trained to go outside via doggy door. Our newest show hopeful came to use at 13 weeks completely litter trained. I usually try to pad train my show pups just because it makes it easier for travel but I tried litter with my 6mo because she isn't reliable with pads & she took to litter training & uses the box perfectly! She will go outside every now & then but for the most part uses the box...as does my 4mo. Saying that I'll also litter train any puppies we have down the road--they just seem much more reliable starting from the get go.
For litter...go with a 100% wood pellet. They're completely safe & you can use pellets you burn in pellet stoves so long as they are again, 100% wood. It's almost the same thing as feline pine but not all pine for the most part but...feline pine is like $5 for a 7lb bag & the pellets for pellet stoves are $4 for a 40lb bag so you do the math.
Litter is a bit messier than pads but being more reliable means more to me than less mess. But also, if you figure you only need to change every few days compared to once or twice a day (with taking out poops from the litter box as needed of course) it really equals out to be the same amount of "work".
At any rate...good luck in your decision!