I've used both...
I have a TennisTutor 4+ that I own and enjoy for its performance and weight. I can easily lift it in and out of my vehicle myself when going to a public court. I will hit for a few hours, and never have used the battery up, so it can go for quite a while.
I belong to a club (indoor courts) that owns a commercial playmate. While I'm sure the quality is probably better, at least you wouldn't know it. As a matter of fact, the few times I've tried using the club machine (Playmate), I was frustrated as I was trying to have it only send me the same consistent ball. It was impossible. I set it to always give the same ball, but one would go into the net, the next a half foot above the net. I'm sure it must be in need of service, but after using my very consistent Tennis Tutor, I was surprised and frustrated that I couldn't get the more expensive Playmate to just give me a consistent feed.
Again, I'm sure there must be something wrong with the club's Playmate, but don't be thinking you have to get one of those. The Tennis Tutor 4+ has a lot of features in a portable, battery powered, fairly lightweight (I think 46 lbs) unit that has worked great for me since I bought it a couple years ago.