If what you are looking for is to do a great deal of damage, I recommend the sentinel, it is like a berserk, a lot of damage and it is fast, but unfortunately that is where the problem is, in terms of defense it is mediocre unless you know how to use it, something that I never managed to learn. On the other hand, the shadow is more versatile, with more variety, and it has certain abilities that can seem like a cheat because it allows you to avoid certain attacks very easily, which gives you a much more decent defense than the sentinel, but in terms of speed , aggressiveness and damage, does not compare with the sentinel at all. My recommendation is that you use in the shadow, it is easier to master, but as with everything, it is better that you try the 2 and draw your own conclusions, or simply use the one that catches your attention