I would say those all are good and can help, just be careful because too many spam links can hurt you. I would send out some of those and then wait a bit, because google seems to be indexing backlinks a bit slower, thats what happened when I did a similar blast.
Blog comments might be riskier but if the blog is not highly spammed it should work fine. Its funny because your asking that question like you have other options. Sure there are other ways to do SEO, but really you have 2 options.
GO for long term, high quality links, which I wouldnt even know where to begin haha
Go for spammy SEO methods, which is easier and also works usually decent on low competition.
It seems like you are going for method #2 which is fine, but if thats the case you really just gotta try it out and see the results, because those seo methods aren't as guaranteed as they used to be.