If you want reliability and power in one package, then DBPOWER G15 12Volt is what you are looking for. It is equipped with advanced features to jumpstart vehicles. It can start up to 8.0L Gas and 6.5L diesel engines.
Stanley J309 JUMPiT is one of the best car jump starters with a lot of features that provide high-end performance. It comes with many power connections so that you could also easily power up all small devices/gadgets besides car batteries.