Prado all the way.
when you pay for toyota you also pay for best R&d in the automotive industry.
basically all three are for completly different 4WD class.
X-Trail is Sub/Semi SUV and equvilant to RAV4, CR-V , Santa-fe, etc. tyical 5 seater , soft roaders.
Terracan on the other hand is a capable but lacks the top end power, it dose competes against pajero , prado , pathfinder but on the basis of "best value for the money".
prado on the other hand is competing against Pajero , pathfineder etc and is a constant segment leader in serious off roading.