I’m kind of struggling with the same issue. All I can tell you is I juggle a few things… I really like Trainerize, BUT they aren’t set up for nutrition YET (at least they claim they will be one day). Also, trainerize has a monthly fee. (Which I don’t mind too much) I also use dotFIT. They have the nutrition tracking but their workouts aren’t as nice as Trainerize and it’s not an app you have to go online on your phone. amStatz is also pretty good. I feel as if amStatz is like a happy medium of the two… Hope that helps.
I send my workouts (which come with the photo of the client doing them) as a PDF file, and my client tells me she can pull it up on her phone and follow the workout.