Sorry to come so late to this thread, but I just wanted to put my own list forward. I revised it from a version I had put up on another forum. It's pretty long, but I think it covers just about everything.
One Piece (LA voice pool):
Luffy: Anthony Pulcini (He has experience and he is relatively unknown, so it works well in giving Luffy a distinctive voice.)
Zoro: Lex Lang
Nami: Colleen O'Shaughnessey
Usopp: Johnny Yong Bosch
Sanji: Skip Stellrecht
Chopper: Stephanie Sheh
Robin: Bridget Hoffman
Franky: Steve Blum
Whitebeard/Edward Newgate: Douglas Rye
Ace: Yuri Lowenthal
Smoker: David Lodge
Tashigi: Kate Higgins
Shanks: Mark Hamill
Ben Beckman: Michael McConnohie
Yasopp: Kyle Hebert
Luck Roux: Kirk Thornton
Mihawk: William Frederick Knight
Marshal D. Teach/Blackbeard: Richard Epcar
Lafitte: Jack Bauer (The VA, not Keifer Sutherland!)
Van Auger: Quinton Flynn
Jesus Burgess: Phil Lamarr
Doc Q: John DeMita
Sengoku: Michael Forrest
Aokiji: Phil Lamarr
Donquixote Doflamingo: Doug Erholtz
Dragon: Tom Wyner
Gol D. Roger: Steve Kramer
Vivi: Danielle Judovits
Rika: Sandy Fox
Boodle: Ralph Votrian
Kaya: Michelle Ruff
Nojiko: Tara Platt
Genzo: Michael McConnohie
Dory: Peter Lurie
Broggy: Neil Kaplan
Dalton: Jamieson Price
Dr. Kureha: Barbara Goodson
Kohza: Tony Oliver
Pell: Richard Cansino
Chaka: Derek Stephen Prince
Igaram: Wally Wingert
Cricket: Daran Norris
Masira: Doug Erholtz
Shojo: Jerry Gleb
Wiper: Dameon Clarke
Laki: Tara Platt
Kamakiri: Tom Gibis
Braham: Liam O'Brien
Aisa: Kate Higgins
Gan Fall: Bill Morgan
Paulie: Doug Erholtz
Zambai: Dave Wittenburg
Lulu: Kyle Hebert
Tiletsone: Fred Tatasciore
Oimo: Kirk Thornton
Kashi: J.B. Blanc
Iceburg: Patrick Seitz
Garp: Richard Epcar
Coby: Mari Devon
Helmeppo: Liam O'Brien
Kokoro: Barbara Goodson
Chimney: Melissa Fahn
Bellemere: Megan Hollingshead
Dr. Hililuk: Michael McConnohie
Saul: Devon Bowman
Dr. Clover: Paul Eiding
Olvia: Bridget Hoffman
Koushirou (Zoro’s Sensei): David Lodge
Norland: Liam O’Brien
Great Warrior Calgara: Tom Wyner
Tom: Michael Reynolds
Buggy: Charlie Adler
Alvida: Mary Elizabeth McGlynn
Mohji: John DeMita
Cabaji: Stephen Apostolina
Kuro: Dave Mallow
Arlong: Jeff Glenn Bennett
Hachi: Steve Blum
Chu: Dave Wittenburg
Kurobi: John DeMita
Crocodile: David Keith
Mr. 3: Steve Staley
Miss Goldenweek: Jessica Straus
Mr. 5: Phil Lamarr
Miss Valentine: Jennifer Sekiguchi
Mr. 4: Lex Lang
Miss Merrychristmas: Susan Silo
Mr. 1: Phil Lamarr
Miss Doublefinger: Gwendoline Yeo
Mr. 9: Peter Doyle
Miss Monday: Sandy Fox
Bellamy: Derek Steven Prince
Sarquis: Kyle Hebert
Lilly: Lara Jill Miller
Enel: Crispin Freeman
Ohm: Paul St. Peter
Shura: Sam Regal
Gedatsu: Kevin Michael Richardson
Satori: Dave Wittenberg
Foxy: Kirk Thornton
Lucci: Terrence Stone
Spandam: Dave Wittenberg
Kaku: Michael Lindsay
Kalifa: Karen Strassman
Blueno: Jon DiMaggio
Jabura: Kyle Hebert
Fukuro: Saffron Henderson
Kumadori: Wally Wingert
Merry: Tom Gibis
Ninjin: Mary Elizabeth McGlynn
Tamanegi: Michelle Ruff
Piiman: Saffron Henderson
Johnny: Travis Willingham
Yosaku: Sam Regal
Fullbody: Yuri Lowenthal
Zeff: Fred Tatasciore
Patty: Wally Wingert
Carne: Kyle Hebert
Chabo: Mona Marshall
Doctor Nako: Doug Stone
Conis: Julie Ann Taylor
Morgan: Douglas Rye
Jango: Quinton Flynn
Sham: Dave Wittenberg
Buchi: Steve Blum
Don Krieg: Jon DiMaggio
Gin: Kirk Thornton
Pearl: Daran Norris
Mr. 2 Bon Clay: Mark Hamill