1. The most important thing about buying a new
bike is to make sure it fits. The only way you'll know if the bike is right
for you is to size up the bike and make sure that the bike's geometry matches
your body's geometry. Ask questions and do some research.
2. If possible, try to find a shop that will
let you demo the bike on real dirt. Five minutes in a parking lot won't cut
it. You wouldn't buy a car without a real world test drive, and a bike should
be no different.
3. Don't belive the hype. Just because
your favorite rider or best friend rides a certain bike, that doesn't mean
that's the best one for you. Have an open mind and be realistic about your
needs and ability.
They're both going to have really high front ends. They strike me as bikes with a more AM attitude.
Really, it's try both (or as many as you can) and buy your favorite. I'd suggest trying some hardtails with 100 mm of travel while you're at it. Make sure you really want long travel and a slack head angle.
What are you riding now?
"Don't buy upgrades; ride up grades." -Eddy Merckx