I was actually thinking of a similar thing with this post question.
In the end, I did a bit of both. I 301'd the best domain and got very good results after about a month, the other domains I am slowly bringing back to life thanks to the Wayback Machine, downloading the old site, doing a bit of on-page SEO and hosting on cheap but popular hosting.
I am working within a very specific niche and for that, I'd say is where the magic lies with the 301. Ultra relevant, ultra-clean anchor links—is where it's at.
But the bringing back to life bit doesn't have to cost much money, but it does take time and effort.