If Ophelia was a stronger person she would not have come to such a tragic end. But others suggest that the rejection by Hamlet and Polonius' sudden death made her tragic end very understandable.
I don't think it is fair to Ophelia to consider her weak. Hamlet is weak too, in some ways. Both of them are young, and faced with very difficult situations. If Gertrude had been looking out for them, things might have ended differently.
First, concerning your question about Ophelia in Shakespeare's Hamlet, the two views are not exclusive. Even if Ophelia is a "weak" rather than a "strong" person, her fate is no less tragic. A weak person's tragedy is no less tragic than a strong person's tragedy.
Also, the question, as far as the play as a whole is concerned, is largely irrelevant. What matters is that Ophelia is dominated by her father and brother, abused by Hamlet, and suffers the abrupt death of her father at the hands of her lover. This leads to her mental breakdown and her death. Whether or not a mentally stronger person could have survived what Ophelia suffers is irrelevant. That might make for a good topic in a psychology class, but it's largely irrelevant when discussing literature.
If you must choose, however, you could choose either view. If Ophelia would not have fallen into her role as a female in a male-dominated society, if she would have been more assertive, if she would have refused to be her father's stooge and spy on Hamlet, and if she would have been stronger mentally, she could have survived the play. I don't know how anyone could argue against that.
If that were the case, though, the play wouldn't be the same play, and it is a play, not real life. Ophelia is how Shakespeare wrote her. She's not real. She can't change.
At the same time, suffering what she suffers, Ophelia's fall seems to make sense. Hamlet suffers from depression, things are rotten in Denmark, appearance and reality are so mixed up that no one really knows what's going on, and Ophelia suffers what I've already mentioned above. Her death is no surprise and seems motivated.