Those are all very nice bikes, and rather spendy for a first bike (at MSRP, but I am assuming you may have some price breaks in your sights). The Trance and Intense have a lot of travel for a first bike and are thus differentiable from the Cannondale. Having more travel means they will handle rough stuff somewhat better and rough downhills quite a bit better, than a bike with less travel in the front and rear suspensions. They will also be harder to climb with, and maybe a bit slower on the flats because the suspension will dissipate more of your pedaling energy. Because of this, the Cannondale would probably be perceived by most as closer to a general, “starter” bike.
You can’t really go wrong with any of these, unless they don’t fit you or suit your riding style.
What type of riding do you plan to do and where are you? Do you ride now? You can grow into a bike, but the risk is that you grow into a bike that doesn’t suit you or your style of riding.
Marin has some somewhat less expensive (at least MSRP) “trail” bikes (trail has become the word for sort of general mountain biking, as opposed to cross-country, which tends now to mean racing on relatively flat trails, and all-mountain and downhill, which contemplate the most extreme trail riding) in the Rift Zone (29″ wheels), Hawk Hill (27.5) and B-17 (27.5 +). The Marins have modern, mid-level components and comply with most of the current standards, so are very upgradeable and are available in 3 component levels, all of which are quite decent, the two lower “trim levels” are under $2000 in all of these (the B-17 might be a hair over).
If you can at least sit on, and preferably at least parking lot test ride, any/all of these, I suggest you do so.