Revive a dead site or make a new one?

I have a few domains that have around 100 articles each on them, but I have not touched them in around 12 months.

The rankings on most of them have gone down.

I want to shift my focus back to niche sites for a while as I have been doing other things over the past year.

Should I try to revive the sites, or just start from scratch?

I'm, thinking that I should revive them, due to them being aged and having a few links on them, but since traffic has plummeted on them I am thinking that Google may not like the domains and would struggle to rank on them.

What are your thoughts?

Revive definitely. Google will reward when it ll see activity in right direction.

Revive is the right option here

As everyone else said, revive.

The best option for you would be to revive a dead site

Go for both,
If you're referring to just a few links on each, the expenses shouldn't be that high,
All depends on the keywords/niche & your budget as well, i normally spread my eggs for a couple of websites per niche

Depends on the cause of death. If it died of old age, then it's better to revive. But if it died of a penalty or of a negative SEO done by competitors, then it's better to create a new one from scratch.