I gotta go with Dean Martin. Sinatra’s voice is like silk but Dino’s is like a comforter you can wrap yourself up in on a winter night. Frank and Sammy songs are phenomenal but I think Dean’s humor is what puts his just a half-step ahead. And lastly, out of the big 3 (Sinatra, Martin and Davis), Dean seems like the one that might actually come out to the Sands bar and have a drink with you.
That’s technically the second incarnation of the Rat Pack. The first was headed by Humphrey Bogart and Lauren Bacall, but included Sinatra, Judy Garland, Swifty Lazar, David Niven, Katharine Hepburn, Spencer Tracy, Cary Grant, Rex Harrison and others. Of those, Bogart is clearly my favorite. Rick Blaine can do no wrong.
For the second, and more widely known version of the Rat Pack, Martin would be my favorite of the big 3. But I have to give the nod to Peter Lawford even though he was basically kicked out early on.
My vote would be Sinatra in both versions of the Rat Pack, although Bogie would be a close second in the first incarnation. Frank had immense talent, longevity, and moxie, even if he wasn’t the greatest actor to ever live, and pretty much did whatever he wanted, with whomever he wanted, including mobsters, and mostly got away with it. He lived the fullest life I can imagine anyone living.
Joey Bishop.
Willard
Re: Rat Pack #2 - Lawford was definitely the sleaziest. Davis, Jr. probably had the most talent. Sinatra was caricatured in the most WB cartoons, Martin drove the most cool cars and nobody really cares about Joey Bishop.
Agreed!
I have to agree. I liked his style and his voice.
Certainly up there.
Dean was so cool - he is the best. Sinatra was also cool, but dangerous. It would be like having Tony Soprano for a friend. If you got too familiar you might get that icy stare. Oops!
I like all three of their musical talents. Dean seems the “warmest” and Sammy seems the least sleazy.
Also, Angie Dickinson should get a mention from the “mascot” grouping.
Another Dean Martin fan here, for the same reasons others have given,
As a side note, I’ve been to several of the Rat Pack tribute shows in Vegas. At one of them we tipped the maitre’d and got stage side seating. The Dean Martin impersonator leaned over and sang one of his songs to my wife. 
I really liked all of the big 3, Dean, Frank & Sammy.
Of the lesser pack members, does Don Rickles count or not? Way more interesting than Joey Bishop and funnier.
Was Angie Rat Pack or Rat Pack adjacent? Also I thought Shirley MacLaine was also Rat Pack adjacent?
Dean was the coolest. He was probably the best actor of the bunch when he allowed himself to be. He also had the most interesting dichotomy between his public persona and his actual personality.
She was much more than adjacent. She was very good friends with Sinatra and Martin and she was in Oceans Eleven. She claims neither ever hit on her and were very protective of her. I believe her since she named everyone else she slept with.
Which she?
Sinatra was occasionally brilliant as an actor. Manchurian Candidate, Von Ryan’s Express, Man with the Golden Arm and From here to Eternity are the 4 that come to my mind fast.
The only Dean Martin acting job that rivals those I can think of was Rio Bravo.
I just saw Airport again recently. I liked him in that, although it probably wasn’t the most demanding role.
Shirley. She hasn’t been shy about naming names so I tend to believe her when she said Dean and Frank never hit on her.
He held his own sharing the screen with Montgomery Clift in The Young Lions.