GTMetrix and Pingdom vs. Google PageSpeed Insights

I have experienced an interesting situation this evening. I was looking around for ways to improve my Wordpress site and found a plugin that was to improve Google Page Speed Insights scores. Well, the new plugin did well as my Google PSI scores went from 65 on mobile to 87. And desktop scores went from 74 to 93. This is the first time I've had green colors for my page speeds on the Google PSI. I don't use Google PSI very often as I mainly use and to test my website optimizations. Most of my homepage loading speeds at GTMetrix and Pingdom are around 1.0 to 1.4 seconds before installing the new PageSpeed Insights plugin. After installing the plugin GTMetrix scores went up to 2.9 to 3.2 on the homepage. Pingdom scores went higher than usual and up to twice as slow with Pingdom. :-(

So, while Google PSI says my site got better it has become noticeably slower to the eye as well as to what GTMetrix and Pingdom both say. It seems Google PSI has a different idea of what is a better user experience. Anyway....

So, my question is which one of these page speed websites should I pay attention to? Should I do what makes my site faster on GTMetrix and Pingdom or do what gives me a better score on Google PSI? Like I said, at times I can see with my own eyes that the homepage is slower with the new plugin that gets me a better Google PSI score than the other two that are GTMetrix and Pingdom?

I'm not a big fan of Google, so I tend to lean toward going with GTMetrix and Pingdom. I simply don't think Google is as good as they are made out to be. I see really poor search results with their site. Yet, I know, they are the one who brings the most traffic to websites for reasons I'll never understand. Anyway, which one would you optimize your site for? The GTMEtrix and Pingdom or for the Google PSI score?

One note upfront is that the plugin I found tonight it called PageSpeed Ninja in case anyone wants to look it up and try it out.

Thanks for any advice. :)