Friendly is more of a cham to cham basis just like dog/cat personalities. Hand raised (not farm raised) normally are friendlier and want hand rides.
In terms of easy to care for, id go with the veiled. They can survive a wide temp variance and humidity. They also will eat some fruit/veg so they are alittle easier to keep a health diet.
Panthers are another excellent pick. They are alittle smaller, little less aggressive, and alittle more active than a veiled. This is splitting hairs. Panthers may be healthier just due to the massive imbreeding of the veiled. Most of the panthers sold here you can see picks of mom and dad and its the closest thing you will get to "papers".
Another "hardy" cham is the Oustalet. I have one and they are very mellow and survive in floridia just fine. The down side is that finding a captive born is hard. I bought a floridia wild caught baby, and 90 days later 2 hand raised clutches showed up on the forums. The Oustalet is not a very pretty cham(bark rocks dirt), but its dino like and the largest sane species you can get(next size up species is $2k).