I’m going to give you my thoughts and some guidance for those who are still sitting on the fence.
The most common problem and trouble people are facing with Yoast is that it offers a list of guidelines for SEO and readability. It also gives you a score and tell you whether the content you just wrote is good for SEO and whether it’s reader-friendly.
In this way, it seems like a pretty good plugin. But many people are over-concerned about their SEO score for every post they write. So they start to find the guidelines very restricting and irritating.
For example, there are guidelines like your keyword should be at the front of the headline, which many people find it impossible sometimes. There are times where putting your keyword at the front of the headline just looks weird.
Also, it ranks you regarding your keyword density, whether your KW appears in first paragraph, etc.
What about All in One SEO?
AIO SEO is the default SEO plugin. There are no complicated guidelines like Yoast which may confuse and overwhelm beginners.
To be honest, these 2 are the best SEO “plugins” for WordPress. They both do a great job in SEO settings. Both have their pros and cons. If you are using any one of these, you are doing good.
I don’t see the need for you to be concerned about which plugin to use or switching plugins. Stick with the one you are using now and concentrate on creating awesome content.
If you are using Yoast, remember don’t be restricted and over-concerned by the “guidelines”. You will and SHOULD NOT be scoring very good every time because your contents are different.