Peak current / engine size rating — Higher is better (for bigger engines)
Battery capacity / jump-start count — Ensures multiple uses on one charge
Multi-functionality — Power bank (USB), LED torch, sometimes air-compressor, DC output etc
Safety protections — Reverse polarity, short-circuit, over-current, etc
Portability & local availability — If you’re in Nairobi / Kenya, make sure local stock, service, delivery.