We replaced our audio panel as part of a recent upgrade, and also considered both PS Engineering and Garmin.
FWIW, I've always been impressed by PS Engineering. They do one thing (audio panels) and they do it exceedingly well. Certainly no complaints in any of my experiences with them, and the president of PSE even gave me some info to help my decision.
*IF* you don't have a Garmin GTN-series GPS and you don't ever intend to get one - Get the PSE. You won't regret it.
That said - We went with the
Garmin GMA350c. We also installed a GTN 750, and I'd be even more strongly in favor of the 350c if you have or get a GTN 650, for one reason: The "Telligence" voice command system. Forget any impressions you may have gotten using the demo at an airshow - It's not engineered for that environment and really doesn't demo well in a tent with fifty other voices in close range, but in the airplane it is FANTASTIC and really makes up for some of the klunkiness of the GTN's touchscreen UI.
We now have an additional "PTC" (Push To Command) button on both yokes, and all you do is hit PTC and then talk to the audio panel and/or GPS. It's way faster and easier than most of the same functions using the touchscreen, and no worries in turbulence.
For example: You boot up, hit "Flight Plan", enter and activate your flight plan, and of course you want to go to the map. Without the 350c, you hit the "Home" button (or the on-screen Back button) followed by the on-screen Map button. With the 350c, you just key the PTC and say "Show Map." You can instantly switch to any screen in the system with a "Show xxx" command, even sub-screens ("Show destination NOTAMs"). You can say "Tune nearest approach" or "Tune destination ATIS" instead of looking up frequencies and tuning them manually, which saves even more time.
There's some "Show" commands that will pop up a window in the top row of the GTN briefly. "Say MSA" pops up a minimum safe altitude, for example.
There's also some "Say" commands where it'll verbally reply to you. "Say time to descent" or "Say winds" for example.
You can control the audio panel as well. "Select Mic One."
And, some general commands like "Create waypoint here" or "Zoom In" or "Scroll Down" type of stuff.
Oddly enough, one of the biggest reasons we wanted the GTN 750 over the 650 was so that the entire keyboard would fit on-screen, but between the GMA350c and the FlightStream, I haven't used the keyboard yet at all!
Highly recommend it. Even our avionics guy, who tried to talk us out of it initially, was impressed enough after seeing ours in action that he wants to install one in his plane now.