To me the problem with the "greatest at each position" debates is that invariably they judge players on about a 90/10 split between offense and defense. Yeah, such an assembled team may not ever have to worry about defense because they could out bash any opposition, but I have a hard time ignoring defense to such a degree because it's half the game.
That's why I'll take Ozzie Smith at SS even with his 28 career homers. If not The Wizard I'd go with someone like Luis Aparicio. I agree completely about Brooks Robinson at 3B, he'd be my guy there too. It's hard not to go with Johnny Bench at catcher since he revolutionized the position. He was the first to use a hinged catcher's mitt and the one-handed catching style that everyone uses now. Before Bench everyone used the old style pancake catcher's mitt and caught two-handed. And he retired as the most prolific power hitting catcher in MLB history.
I like the Mick in CF, but it's hard not to go with Willie Mays - who was widely considered the best all around player to ever play before Bonds discovered steroids. Joe Dimaggio is obviously another great option in center, and I think it is easy to forget just how dominant offensively *and* defensively Ken Griffey Jr. was before his body started breaking down. I also really like Ichiro. I'd take Ted Williams in LF over Shoeless Joe, or as much as I can't stand him (and never could) - Barry Bonds -lol-
No arguments from me about Gehrig, Hornsby, and Aaron
Obviously we're talking about all-time greats though and they're all amazing players.