I personally prefer PS2. I've got at least a dozen PS3 engines (many early PS3 when they were nearly the same operationally as PS2). I've got 4 PS2 locos I'm trying to keep running - 2 steam, and 2 diesel.
Issues I have with PS3:
1) The wireless drawbar with steam. Structurally, good. Electrically, really bad. I have had nearly non-stop issues with it. In fact, my only PS3 steamer is at my tech being gutted and turned into a conventional engine. The drawbar has had some issue that causes it to lose control and emit loud "rapid fire static" out of the speaker. The boiler board has been replaced. The wire harness in both the engine and tender for the drawbar have been replaced, several, several times. Each time, it would solve the problem temporarily then back to issues. In addition, I've also replaced the actual drawbar and tender socket several, several times. I'm sick of dealing with it. I want to run it, not look at it. I look forward to getting it running as a conventional engine again.
2) PS3 steam "no coast" issue. Take a new PS3 steamer. Run it in conventional. Hit the direction button (or throttle down). You'll be witness to a rather violent "stop". Unlike the early days, the new PS3 steamers don't gently "coast" to a stop. They now totally lock up and skid to a stop. I've derailed trains, shredded traction tires, and had a motor start skipping gear teeth. I went directly to an MTH executive about this. They said they are aware of the issue and were not willing to invest time and money to resolve due to most folks running DCS. PS3 diesels also have this issue ONLY when the smoke is on. Since I don't run diesel smoke, it is a non-issue for me. I prefer steam. MTH is making what I like and have the means to purchase but I refuse to touch a PS3 steamer. Lionel has my steam money.
3) Various quirks with PS3. Engines will start up in conventional immediately vs. waiting 20 seconds to charge only to die when attempting to run. I have also found the structural build quality isn't what it really used to be. Thinner wire used for details, etc, etc.