I don't think this is even a question nor should it be an argument anymore, and hydrogen fuel cell locomotives are hands-down the winner. Sure, there is a lot to go for clean mass production of hydrogen, but the problem is not unsolvable. It is similar to nuclear power. They are totally safe (Fukushima and Chernobyl are the result of degrees of neglect and human error), but have the problem of nuclear waste. It is expensive, but can be solved. Additionally, nuclear power can also make clean hydrogen. Back to hydrogen fuel cell locomotives. Unlike the Hindenburg, these locomotives and other HFCVs are more likely to use solid and safe storage of the hydrogen unlike the Hindenburg. As for battery-electric locomotives, they are rather impractical. If you want more range, you need to make the battery pack bigger. Bigger packs mean more weight. Bigger packs also mean more pollution to mine the stuff needed for these batteries. The only real practical things I see battery-electric locomotives can do is shunting, switching, commuter passenger service, and local freight. Long-haul freight trains and high-speed trains like hot shot freight trains and express passenger trains would be completely out of the question. Additionally, there are fires. While it would be comparable to a diesel locomotive fire, I believe a burning battery locomotive would also put toxic chemicals and metals from the battery, and the battery is a large one, too. That fire, probably unlike a diesel, would take a lot of water to put out. Take a look at the news on Tesla fires. I believe a battery-electric locomotive would take like an entire fire department to put it out. Sure, you can probably just use a fire blanket to save water. However, after a fire on a battery-electric locomotive is put out, there is a chance it will come back again, unlike diesel locomotives. Let's also not forget that weather conditions affect performance. Combustion engines and fuel cells perform far superior to a battery locomotive in winter. During the cold times, Tesla ranges decrease by like a lot. Imagine this with battery-electric locomotives. The battery also needs to operate other stuff like heating, air conditioning, etc. other than powering the motors. Whoever has plans for battery-electric locomotives on their long-distance roster is stupid. Hydrogen fuel cell locomotives are the safer option, and have more benefits. Or maybe you can electrify your rail lines.