My MatchPen R has been great, I use it often for the majority of polishing due to the size utility of it. My rear button did go out after a few years and ScanGrip warrantied it without issues and sent me a new unit. I recently picked up the Meguiar's MT103 Sunlight 3+ which is made by ScanGrip and is the direct alternative to the SunMatch 3, I've also been enjoying it. You can now find the Meguiar's MT103 for around $99, which makes it by far the best value ScanGrip at that pricepoint. Separate buttons for brightness and color temps, and the memory function means you can turn on/off/on with one button and it will save all your previous settings when you next turn it on. No more hunting through light modes/brightness every time you want to turn it on/off like some other lights.
The MatchPen R you can adjust color temp and how wide/narrow the band of light is, but no brightness adjustment. Out of the box I think the brightness level is pretty spot on. The MT103 has full adjustability with a range of color temps and brightness levels. I wanted the MT103 as soon as they released it until I saw the pricepoint was around $250 or so. When I saw them drop down to $99 recently I bought one instantly. Need some more time with it to see if I'll grab for it over the MatchPen R. I don't have any experience with the smaller MiniMatch.