In my opinion Mark Waugh is the most talented batsman and best fielder,
For best fielder, he may JUST edge out Greg (highly contentious, though) but for pure talent, Greg Chappell is surely above Mark Waugh. He's an example of what can happen if raw talent is applied with mental toughness and consistency. Put it this way; there's a reason he averaged more than 10-runs-per-innings more than Mark Waugh. Greg rarely had 'off-days'. He had a fun of 5(6?) ducks in a row but it's difficult to remember any other form slumps in his career. At their best, they were both great to watch but I'd have to say that Greg was a 'better' batsman.
Also, you state that you'd choose Steve but not Mark Waugh to bat for you life? I doubt you've seen much of Greg Chappell because he'd certainly be a strong contender for this too.
I'd say that the Chappells contributed more to Australian cricket (call me cynical, but I doubt Steve Waugh would have signed for Packer cricket in the day but would have preferred to play on in the traditional Test side) individually but Steve and Mark Waugh probably contributed to the success of the Aussie cricket team in the 90's collectively more so than Ian and Greg did when playing together.