AI plays Shriekers very defensively, and thus very poorly, thus that screenie above.
Shrieker deck works very well for Top50, very fast, very simple. Minute to a minute and a half games are very common. I've played a lot of decks grinding Top50, which is what I do most, and it seems the most efficient for me.
Shrieker is also fast to build from a starter deck, to farm AI3, then once you're about half upgraded you can start farming Top50. It's also so simple, grinding is boring, and having a deck that you don't have to think too much about is helpful when you're going other things at the same time. I chat, or play games on my other PC while I grind out games. More complex decks are much more fun when I am focused on playing, but simple decks lead to less play errors on my part when I am distracted or interrupted.