I have been on both. I have always taken Citalopram (Celexa) for my AD which is like a wonder drug.However, it made me manic my pdoc wanted to add a mood stabilizer. I had tried the quetiapine first, but it made me like a zombie, excruciatingly tired all the next day, i even fell asleep at work. I also had a panic attack while on it because it really made my body feel strangely anxious. It helped me sleep, well..actually it felt like i woke up from being comatose, not really good sleep. I was switched to abilify very recently and have started on a very very very small dose, i haven't noticed any side affects so far. What i was told is the abilify not only acts as a mood stabilizer, but it also boosts the effectiveness of antidepressants. I was also told it has a way lower chance of causing weight gain.