I have had two 4", one 6", and a 6.5". One 4" was stolen. I still have the rest. I shoot them a lot.
The 4" are handier and easier to carry, that is what I use for HD.
The 6" or 6.5" can feel kind of nose-heavy, but the felt recoil is less. They are also more accurate for me, but that might just be me. I shoot a lot better with a longer sight radius.