Glans size
Depends if you see tight as a bug or a feature. To me, tightness just reminds me its there, which is part of the enjoyment. My 28 mm ones have never fallen off and squeeze me pleasantly when erect. I can wear them indefinitely.
I have tried my wedding band (~20 mm) but only for short periods. The first time I did, the urethera was completely blocked, but not on subsequent tries.
I have also tried o-rings of various sizes, but cannot recall for how long, probably measured in hours rather than days. Since they are flexible rather than rigid, the may be more comfortable for a given size. I like the look and feel of metal now.
Okay, lost one last night. :-( In my defence, I was in cold-ish water and needed to take a leak. As I pulled my equipment through the leg of my swimsuit, I inadvertently knocked it off and into the same below. Shrinkage may be a factor in addition to bumping it. No way to locate it given the cloudy water. Now thinking 24mm may be closer to the ideal size than 28mm but that may not be an of-the-shelf option. Or I could just be more careful...
I wear a 28mm solid ring which I can wear under my foreskin for a long time and all day at work, I did try a 28mm open cuff type but found it difficult to wrap my foreskin over it and with shrinkage it does fall off, so no long time wearing for that one. I suppose for those cut guys shrinkage can be a problem and the risk of it falling of and even worse loosing it altogether and not having it to wear. I do like it when I get erect and feel the tightness under my gland and head and the knowledge that its there which makes things get harder.
Andy
I found that my foreskin kept rolling over the glans ring. This defeats the purpose of wearing the glans ring in the first place since you could no longer see it. By wearing a tight wide ring higher up, it holds back the foreskin so the ring shows.
https://www.imagevenue.com/ME19AAB2