If you are a fix it yourself person, then the big brands are better, as they will either tow you on the spectacle frame or on their own trucks to where you want, so if you intend to fit a new alternator yourself on your drive for a fraction of garage prices, you want this option.
The cheaper ones use local contractors to recover you to their garage for a fix. If you would pay a garage anyway, you might prefer this.
It is possible to game the system by waiting until all the garages are closed to call it in, then it invokes proper recovery.