I have both a Buckmark and a Ruger MKIV 22/45. After dressing both up with aftermarket parts like Volquartsen and TacSol barrels, trigger kits, red dots, and more, I lean toward the MKIV, but mostly because of the ease of dissassembly for cleaning. Out of the box, I favored the Buckmark, because to me it just looked and felt like a more refined and sophisticated firearm.
Both pistols are far more accurate than I am, both before and after the aftermarket mods. On balance, the pistols perform more or less equally. If I had no intention of doing any aftermarket mods, my choice between the two might come down to price. If the aftermarket mods are a consideration, the MKIV has a lot more aftermarket goodies and support.