You have to decide what is best. You can reduce the choices by dismissing high recurring fees and high initial costs. Also you get to look into what cellular network these are using and dismiss any that you know the carrier has poor or no coverage in your town.

The cheapest tracker I own is a smart phone. I picked up an old android, put in a Freedom Pop SIM (10 dollars) and use their zero dollar a month plan and a free GPS tracker app. This continues to be my cheapest tracker. There are those that want to debate but I will not enter into that debate. It works for me and fits my goals.

As to battery power I added some USB powerbank and done.