Of all the Ruger single-actions I've owned, the OM 45 Colt was tops, and that even nudges out a custom 3-screw Blackhawk conversion to 44 Special and three (four*) different Flat Top 44 Specials.
Cartridge-wise, I love the 45 Colt and the 44 Special, but the 44 won out when I began consolidation of bore sizes and components I needed to source and stock. There wasn't a Charter 45 Colt Bulldog, in other words.
What was so great about that OM 45 Colt is that it was an OM (and I had divested myself of all NMs by that time), it was the right overall size, it didn't have the SBH grip frame (or a Bisley, both of which are way too big for me), and the weight distribution was perfect for very natural handling. Oh, and it was a 45 Colt.
This one was a 5.5" (originally 7.5" - long story), came with the grip frame that fits me best (XR3-RED or similar) and the grip frame being aluminum gave it a weight distribution that made it handle very well for me. It didn't seem as heavy as my OM SBH or my NM Flat Top 44 Specials in the same barrel length, even though it was the larger NM Blackhawk frame.
If I were to make a recommendation to someone else, I'd probably nudge them toward the new Flat Top 45 Colts, with or without an ACP cylinder. I personally stuck with the 44 Special because of one small but important tipping point - I could cast and load for one cartridge for which I could have both a robust, all-purpose woods/trail/huntng gun as well as a pocketable self-defense piece. There was no 45 Bulldog at the time.