I started with SPDs, and they were fine for a long time. At first I had some knee pain, but after a fitting to make sure the cleats were positioned right on my shoes they were okay and I had no complaints for several years.
However eventually the knee problems came back, and then when I got a new bike they were worse, so on the advice of the fitter at the LBS I switched to Speedplays (not sure of the specific model -- X-somethings). They have more float and my knees are much better with them.
The only downside I find with the Speedplays is that it's very hard to clip in and out if dirt gets in the cleats. I bought some cleat covers (plastic covers that snap on) and bring them with me whenever I ride so I can use them if I need to walk anywhere. It's a bit inconvenient, but better than painful knees.
- Gray 2010 carbon WSD road bike, Rivet Independence saddle
- Red hardtail 26" aluminum mountain bike, Bontrager Evoke WSD saddle
- Royal blue 2018 aluminum gravel bike, Rivet Pearl saddle
Gone but not forgotten:
- Silver 2003 aluminum road bike
- Two awesome worn out Juliana saddles