I got both
To me it goes a little something like this.
The smith 642 is the best easiest pocket gun to draw from a pair of jeans that I own. There is no beter example of a quick grocery trip type firearm that will do its job in a pinch. I am good with it because I practiced hard to get that way. It has never had a malfunction of any kind ever period end of story. It is slow to reload for me with speed loaders which I keep with it and throw in a coat pocket. This is even more exagerated because I am a lefty and the lefty reload is moe difficult for me with this gun.
The Beretta Nano is the easist gun to carry that I have ever caried Iwb. It dissapears. It feels like I am carrying nothing. I holds 7 rounds six plus one so that is actually two more rounds before a reload as compared to the 642. I can carry two spare mags with it easier than I can carry 3 speed loaders. It is provng to be reliable with high test sd ammo, and I can reload it much faster.
Honnestly I could not choose between them but If I were going to get one before the other it would be the nano.