We've been playing Old Saloon for a while and, with some recent rule clarifications posted by the authors, I think I have a pretty good handle on character rankings. Note that we always play with 6-8 players and that we do not use the ghost expansion or the role abilities expansion, as they stretch the gametime too long for our window.
SSS: Elena Fuente
SS: Bart Cassidy (A rank in normal game)
S: Calamity Janet, Rose Doolan, Vulture Sam, Vera Custer, Doc Holyday
A: Jesse Jones, Jourdonnais, Sid Ketchum, Bill Noface
B: El Gringo, Pedro Ramirez, Black Jack, Willy the Kid, Slab the Killer, Apache Kid, Tequila Joe
C: Suzy Lafayette, Paul Regret, Jose Delgado
D: Lucky Duke
F: Kit Carlson
For Lucky Duke, we felt that an extra re-roll is weighted too heavily towards bad actions: you still can't re-roll dynamite, but you can re-roll arrows and get more arrows or dynamite (we actually nicknamed this character "Dr. Arrows"). For Kit Carlson, having to keep a gatling die to remove an arrow was not powerful enough to merit choosing a 7-life character (note that the broken arrow die in the expansion may be re-rolled after removing an arrow).
We ended up using house rules on both of those characters. For Kit Carlson, we changed it so that a rolled gatling die would immediately remove an arrow (similar to the broken arrow in the expansion).
For Lucky Duke, I actually created a new character in his place: the aforementioned "Dr. Arrows", whose power is the option to pass any arrows collected from arrow dice remaining on his final roll to player(s) next to him. (He still has 8 life.) So he's similar to Elena Fuente, just not as powerful; Elena can pass an arrow to anyone on the board, can re-roll that die after doing so, and won't proc arrows on herself if she has no arrows and rolls the last one remaining in the pool.
As it stands, we're probably going to have to devise some sort of house rule for Elena Fuente and Bart Cassidy. Elena is the best character in the game by a sizable margin (and a hard counter to Vera Custer, another great character). Bart Cassidy is nearly unkillable at endgame (or if Elena is on his team), and requires opponents to use otherwise inadvisable strategies with the Chieftain's Arrow just to make sure he can't get it.
You forgot to rank Molly Stark.