I have 3; two -3s and one -4.... I think it's personal taste...like the three bears! I think the 3 inch 66s and the 3.5 inch 27s have the same pleasing porportions of barrel length to frame/grip size.

I like my 2.5-inch 66/19s;nothing wrong with them for IWB carry;but short ejector rod.

I really like my 4-inch 66/19s...... but for me a tad to long for IWB carry;

But, with Spegel boot grips and a Sparks Summer Special IWB, I love my 66 3-inchers.My carry revolver of choice since 1988.

I have a 3-inch 65... but I had it tuned for DAO and magna-ported in 86-87.A great gun but,wish I had skipped the maga-port....not worth in for .38P+ and I don't carry magnums in it that much.