I'm going with, "It depends."
Everybody's hands are different, whether that's by size, strength, architecture, medical issues, etc. That's before we consider where and how the gun is carried/concealed.
You're probably going to have to try different grips to see what works best for you.
As for me, the best grip is the original Spegel boot grips. I have a cocobolo set for my 642-1. The palm swells allow the gun to fill the hand without being bulky, but I think they also help with getting the hand on the gun in the proper orientation when drawing. Being smooth wood they won't cling to clothing or add unnecessary drag on the hand as it closes around the grip when drawing, but once you have firm pressure on the grip it's not slippery. I like that.
About the only thing I don't like about them is the finger grooves. With my hands, I almost always end up with my ring finger right on the "hook" between the finger grooves when drawing. Fortunately, it's not a particularly sharp hook so it's not too bad. Generally speaking, I think grips without finger grooves work better when it comes to drawing from a holster.
I tried the Magna and the Magna/T-grip combo, and it just didn't feel right in my hand. I think it had to do with the gaps at the front of the grip.
I've also tried what's been called the "Claude Werner Carry System," which is a set of Barami Hip-Grips, a Tyler T-grip, and a Hogue Handall rubber sleeve. Didn't like that one, either.
Having said all that, my 642 is currently wearing PGS Hideout grips (smooth, no finger grooves). Similar in size to the Magna/T-grip, but the grip fills in that gap at the front so my fingers have continuous material to wrap around. The biggest downside to the grips is that they're not cleared for speedloaders unless you modify them, which I did. The plus side is that they're only about $18-20 from Brownells so it's not a big loss if you screw them up.
I will add that getting my hand in the proper orientation for drawing was not as "natural" as it was with my Spegels. I did have to practice a bit, but eventually got it right. I can now draw with either and have the sights lined up properly when the gun is brought up.
Which brings up another important point. Practice is probably going to do a lot more for drawing properly than how the grip fits you, but grip fit shouldn't be ignored, either. A grip that fits you is going to go a long way towards helping you get the gun properly oriented from the draw.
As far as best J-frame for carry/drawing from a holster, again that's going to depend on how you carry/concealed. In general, though, I think the shrouded or concealed hammer models are probably going to be your best bet as there are fewer potential snag points. Bobbing an exposed hammer spur is another option. Of course, there are several people who carry with exposed hammer spurs and don't have an issue, but I'll stick with my opinion that it could still be a potential snag point during the draw.