What difficulty?
If it's on Nightmare, DW rogue is not very viable - you will die very very easily. 2H warrior with some SnS passives is fairly durable and viable on Nightmare.
Not true. Sure -- if you play heads-in-"I am a warrior!!"-rogue, you get kicked down. If you actually play with the strength of the class, it's pretty easy.
Stealth -- twin fangs -- deathblow -- dead archer. Re-stealth. Repeat.
Besides, why would you get hit as a rogue?
Hello! I have just bought DA:I and I still don't know what class should I take. I am thinking about DW Rogue and 2H warrior. I know its RPG and I should take what I prefer more but I really can't decide. So please answer me for some questions:
1.Is warrior class fun to play? Because I read playing warrior is just boring.
2. Can I play DW Rogue like medium armor warrior ? I mean I don't like stealth classes and I thounk about play it without stealth or using it seldom. ( just as dual wielder warrior in Dragon Age: Origins, but with medium armor instead heavy).
3.Is 2H tree ok? I read two-handed tree is just worse than others.
I really thank you for all your answers guys, greetings 
PS I know I can try all classes but Its require time + I rather want to end game with my first character , you know identify with my hero is really important to me.
1) Reaver warrior is far from boring. Dipping into battlemaster and 2 hander, I got 3 CCS, some AoE and a shitton of damage.
2) You can play a Rogue without stealth, but that's going to be a nightmare before you get Tempest specialization.
3) Yes and no. I find the tree boring, but efficient. For instance, going down the left side to pommel strike (I think it is called...) will give you an almost instant-hit CC which deals hard damage. Also getting Mighty Blow and its upgrade makes it hit for a truckton when an enemy is knocked down. This is especially good thanks to the Battlemaster tree where you can get a knockdown on the grapling hook, and a 30% added damage on knocked down targets.
I, for one, have had no issues on Nightmare on my Rogue or Warrior. Both got their strength and weakness:
Rogue: You need to either plan out an ancounter, or think on the fly. High damage in short bursts. Can do some insaaane damage.
Warrior: As a reaver you need to manage your health carefully. You can brute-force through most encounters.