OP here. Follow-up.

Luckily, I was able to find the right saddle: WTB Gravelier. I cannot say it is the best or most optimal one, because I only tried 9 saddles. But at least I was able to find one that works for me. I bought 2 of these. One for gravel and one for hybrid.

As with all things on the internet, need to take all advice with a grain of salt. Some advice helpful, but some are completely off and not applicable in my case. Just because it works for 1 person (you), doesn't mean it applies to everyone. On the other hand, if there is bike fitter here who has worked with hundreds of people, then that advice might be more credible. So bottom line is that we need to test out saddles in person.

Some things that I found that worked for me:

• First level for comfort, I must have cut off to address my perineum (perineal) pressure, perineum numbness, and penis numbness.
• Second level for comfort, saddle widths have huge impact.
  • Sitbone width measurement is quite useful to get the right size, so manufacturer suggested size based on sitbone width is right on for sizing. Of course that does not necessarily mean the right saddle in comfort. But need to start there.
  • I sit on carboard box and measure my sit bone (ischial tuberosity) to be 125mm. Then I also used aluminum foil on saddle. I can see indentation of my ischial tuberosity to be 120-125mm, and ischial ramus to be around 115mm. Among the saddles I looked at, saddle widths are basically narrow (135), medium (145), and wide (160). Manufacturer suggest medium size for my sit bone width.
  • On the wide saddles, I can see that my ischial tuberosity is too far forward (near area where saddle start to widen); there is no support for my ischial ramus (can barely see the indentation on aluminum foil); and a lot of pressure in the perineum, even with cut out.
  • I also tried 1 narrow saddle (130mm wide). That was really stupid that I changed my saddle at work using saddle borrowed from coworker. I had to ride 1.5-hour home. It was extreme torture. I don't even know why or how, as I couldn't even analyze the situation. There was so much pain in the soft tissue around my ischial ramus.
• Third level for comfort is shape at the top of saddle and near cut-out. Once the pressure on perineum is removed, then this top saddle shape determines how remaining pressure is spread out.
• The side shape, flare, and curvature do not affect me much. WTB Gravelier has wider mid-section and gradual taper to the widest part. I also tested old Specialized road saddle narrow mid-section and sharp flare to the widest part. They both work well and feel very similar.
• Pinching can be a real issue. I tried Specialized saddle with a lot of stitching around the cut out and around gel pads. Even though the saddle shape is comfortable, it pinched really bad.