After years of shooting Pen's and OM's, I branched out into the Olympus RF's and VF's (all of 'em). For several years I made a concerted effort to only shoot the RF's. They were nice. They all have their own character.
But the OM's will always be my first love. The view thru the lens just seems so "real". The OM is easier to use in full manual, which I prefer (For Olympus' RF's, only the SP metered when set to manual). I prefer a wider lens, and take most shots with a 28mm or 35mm. And the sound of the mirror and shutter is just so strong and solid (And I take exception to the lower shutter speed comment for RF's. That might be true for some of those "other" SLRs, but the OM's are too smooth. I actually had more problem with the RF's because of the long release shutter travel needed lock the exposure.)
And the final point, you can't leave the lens cap on an SLR or frame for the wrong lens. Check the post above for the guy who did just that.