There are two key parameters one should determine before deciding on what the best battery source would be for a given portable project:
- What is the normal continuous current draw of the complete project?
- What is the duration you want the project to be able to run for without having to recharge the batteries?
There are a tremendous variety of battery types and sizes available these days, but without those parameters people can only guess what might work best for your project. Help us help you. 
Lefty