Lithium prices are starting to drop. This battery seems to be high quality, will last forever, is lightweight and most important, costs under 400 bucks. If I was starting anew, it would be on the "A" list.
https://www.amazon.com/LiFePO4...amp;ref_=as_li_ss_tl
Here's a good video from a respected youtuber who does this sort of thing for a living. He liked it a lot.