I've never bought a pistol that wasn't great 'out of the box', but some of them I did swap out parts before I had barely put any rounds through them. My CZ's all got Cajun parts and springs, and even Wolf +5 or +10 magazine springs. They work great, but they didn't get much trigger time bone stock.
The pistol that made the biggest impression on me as a shooter 'out of the box' isn't glamorous, but it was the Glock 26. It was my first, and only, Glock. I almost didn't want to like it, since I wasn't in to the Glock hype at all. However, as soon as I shot it at 7 and 15yds, it changed my mind about the platform! I just couldn't believe how easy it was to shoot accurately, from an admittedly novice hand too. I carried it for three years, became proficient with both strong and weak hand shooting, and only got rid of it to fund another CZ. I would recommend a G26 in a heartbeat, I just didn't have any emotional attachment to it. Sell a Glock, and you can just buy another down the road. That being said, the G26 is a heck of a performer bone stock!