I guess it may be handy to have a manual drill if you are stuck in the back of beyond and your electric one fails, but I think I would definately carry a battery drill, complete with a couple of chargers and a few batteries, and chose a system that also supports other devices (I would think a cordless jigsaw could be handy?)
I use the Ryobi One+ 18V system with a selection of drills (standard, hammer, angle and impact driver) plus garden strimmer and hedge trimmer.
I also use the Bosch Green "Easy" products which use a 12V/10.8V Battery and with that one battery system can drive a Drill, Jigsaw, Mini-Chainsaw (great for plunge cuts) as well as a Torch and Vacuum. I also use the same battery to run my Cordless Dremel, plus got Chargers for the batteries that connect to 240V Mains and 12V DC.
I rarely use corded saws and drills now.