Many year ago I bough a cart-style charger-starter.
Figured I’d use the “start” function 2 or 3 times.
Turns out, the “Start” function is all it ever gets used for.
To properly charge a battery, set the charge rate to 2 amps and run it overnight. A slow, deep charge will produce a more durable charge than a 2-hour @ 15 amp.
I would STRONGLY recommend the portable pack type unit. Keep it in the trunk; if you use it, put it on the floor of the passenger side - seeing it there will remind you to charge it (2 amps overnight!).
The additional functionality of air compressor make this a no-brainer.
I used to carry a spare battery, jumper cables, and an air tank when traveling long distances.
Took up a lot of space.
The same functionality is now available in the format of a large purse of small attache case.