I watched ep1 with the English dubs and it ruined it for me. What you said above (bolded) sums it up quite well. If I tried again, which I won't likely, I'd go with captions. Chernobyl was infinitely better.I'm halfway through The Days on Netflix about Fukushima. It's not bad but it's no Chernobyl. Kinda cheesy at times.
Someone earlier mentioned watching the dubbed version because it wasn't bad but I disagree. If you're ok with subtitles, I would probably do that.
I started with the dubbed version and will stay with it because the wife prefers it to subtitles but the dubs sound too American. Some of the voices used for the younger guys sound like California surfers. And I'm not sure how accurate the translations are with some clearly American terminology like "Yo, what's up?" Most of the older guys are ok though.
It doesn't help that I finished four episodes and the main disaster hasn't even happened yet. The initial earthquake and tsunami are in the first episode but since then, it's all about plans to prevent the disaster with a lot of long lingering looks while various people contemplate what to do. Not a lot of sense of urgency in many scenes and a surprising lack of tension. This easily could have been 6 episodes instead of 8.