I have all three: Stevens 350, Mossberg and Remington.
The Stevens works well for me and is much more comfortable to shoot slugs in. And I like the fiber optic front sight. But it is hard to say how well it will hold up, since I only have a couple of hundred rounds of buck and slug through it so far. I got it has a "try her out" gun. I would go with a more proven model for a primary defense shotgun.
Also, you won't find the accessories such as alternate stocks, fore-end light mounts, or replacement parts as easily or in as great variety as the Rem or Moss.
BTW, my dad was a lefty and that is why he got the Mossberg 500. It has a tang mounted safety that is very handy for either right or left. He never had a problem with the right side ejection.
"The ultimate authority ... resides in the people alone. ... The advantage of being armed, which the Americans possess over the people of almost every other nation ... forms a barrier against the enterprises of ambition."
- James Madison