This was a comparison table I was sent by one company when i was researching them last year.
Another device that I thought was worth considering is a laser flare for attracting attention.
The RLL012-01 Rescue Laser Light is a hand-held day and night time laser signalling device that provides a convenient, effective way to signal a rescue party over 20 miles (32 km) away, depending on atmospheric conditions. It's waterproof, rugged design combines the safety of a laser signalling device with the convenience of a flashlight. Unlike pyrotechnic flares, the Rescue Laser Light is non-flammable, environmentally safe, and can operate continuously for 40 hours on a single, long-life, replaceable lithium battery.
Specifications Batteries CR123 LithiumOperating Time on Batteries 40 hoursWaterproof Depth 80 ft (24 m)Laser Diode Red 10,000 hr. meantime to failureSignal Distance 20 miles at night1-3 miles daytime Warranty Limited Lifetime Warranty
www.whitworths.com.au/rescue-red-laser-flare-light