As another former gifted child, IMHO social skills are infinitely more important than academic, especially in preschool.  I happen to be a big fan of Montessori, as both of my boys thrived in that environment.  But I also think one consistent environment is preferable to going back and forth, and I'm not sure how much benefit she'd get out of one day per week of Montessori anyway.  The community school sounds wonderful, and from the way you write I suspect it is your true first choice.  But you're lucky to be torn between so many good choices.