While I don't have them anymore, the largest guns I regularly carried were a 3" 65 and, on occasion, a Glock 23, both concealed. The 65 was a bit easier to carry discreetly than the 23, but neither was particularly difficult with the right gear.
Currently my EDC is a 642, but my only other option is a Beretta 92FS. I haven't ruled out carrying the 92, but I'd have to wait until I can get some suitable carry gear and it's just not a priority right now.
When I worked as an armed guard, the largest gun I carried was a 4" 686, but that was open carried in a uniform holster. The funny part is that the company policy restricted us to .38 Special 158gr LRN. Also, the guns had to remain on site, so none of us knew if they even worked. *sigh*