Cary Chapman makes a style of grips that flare out at the top, filling the hand between the thumb and palm; I have them on my 5.5" Stainless Bisley 45 Colt and really like them. Cary made this pair out of ivory micarta for me back in 2006.
Those are beautiful! I really like Mr. Chapman's grips.
I really, really, really dislike grips with a swell at the top like that. They slam into the joint at the base of my thumb and hurt me like hell. I am far better served by the factory grip profile in the Bisleys. This may be due to injury to that joint as a young man, I don't know... all I know is that grips that are fat at the top are a no-no for me.
The shape and size of the shooter's hand should be the determinant of grip shape, not the shape of the grip frame.
This is not a new debate. Youngsters may not remember the names Bill Jordan and Skeeter Skelton, but these two gentlemen, estimable handgunners both, had very different approaches to revolver grip shape. Jordan had HUGE hands and liked a big fat grip, available today as Herter's Trooper Jordan, and mimicked by the Miculek grip and others. Skelton was a more slightly-built man with long, skinny hands, and he liked a "coke-bottle" shaped grip, available today from Altamont and others.
I've tried both styles. The Jordan types are a mess, as far as I'm concerned. I shoot the Skelton type grips far better, at least on double-action revolvers.
The Ruger Bisley gripframe with factory grips works very well for me. My most-used Bisley has the factory wood grips that I bought it with 12 years ago. I've fired thousands of rounds of heavy .45 Colt ammo through this gun with plenty of comfort.
All you can really do is try grips that you think you'd like, and if they work for you as is, great. If they don't work for you, sell them or carve them to suit.