Most Comfy = most comfy for You , with your hand size & shape , your shooting style , your previous experiences , and your preferences . And this thread has had an order of magnitude difference in price ranges . But there are several classic favorites , when combined with the context of the bulk of the grips .
Pach Compacs are a favorite for being comfortable and good control while being reasonably , excuse the expression , compact .
Uncle Mike's Boot Grips were licensed duplicates of Craig Spegiel , just in synthetic instead of beautiful wood .
The " regular " Uncle Mikes were of note for being usable for a wide range of hand sizes . Not an issue for someone on their personal revolver , only used by them , but an important point for an agency with one style of grips for a fleet of issued guns
For me with XXXL hands , not as secure for twisting with heavy recoil , but within the range of being usable with
38 Spl .
Plenty of K frame RB guns have been fitted with Pach Presentation intended for SB .
Finger grooves are somewhat helpful IF the grooves fit your fingers , but an abomination if they don't .
Other than purely concealment , open vs closed backstrap is a matter of what fits your handsize .