I've went through a few and alot of them fail after a while/don't hold their charge.
Talked with a few AAA service and alot of them recommended this:
http://www.amazon.com/Jump-N-Carry-JNC660-1700-12-Volt-Starter/dp/B000JFJLP6/ref=sr_1_3?ie=UTF8&qid=1453145747&sr=8-3&keywords=car+battery+jumper
These are the best ones I've used after many years working at car dealerships.
https://www.amazon.com/Jump-N-Carry-JNC660-1700-Peak-Starter/dp/B000JFJLP6/ref=sr_1_2_sspa?s=automotive&ie=UTF8&qid=1515590730&sr=1-2-spons&keywords=jump+n+carry&psc=1