Looking at the list:
Kris Joseph
Dionte Christmas
Kenyon Martin
Ben Wallace
Terrence Williams
Darko Milicic
Jamar Smith
Chris Andersen
The way I look at it our biggest needs right now are rebounding, low post scoring and interior defense. KG is the only player on our entire roster that gives us all three of those things, and if he gets hurt or in foul trouble we are in trouble.
In order to gain these things, the first thing that's requried is it has to be a big, so that cuts the list down to:
Kenyon Martin (6'9" 240 lbs)
Ben Wallace (6'9" 240 lbs)
Darko Milicic (7'0" 275 lbs)
Chris Andersen (6'10" 228 lbs)
Next (and IMO most importnatly) they need to be good rebounders, so lets look at rebound rate:
Kenyon Martin (Off: 6.1 | Def: 17.4 | Tot: 11.6)
Ben Wallace (Off: 9.3 | Def: 24.2 | Tot: 16.3)
Darko Milicic (Off: 7.9 | Def: 14.3 | Tot: 11.1)
Chris Andersen (Off: 11.6 | Def: 22.5 | Tot: 17.2)
All four guys are better rebounders then out current starter (Bass), with Wallace and Anderson the standouts.
Next, here's how they compare in terms of scoring in the paint. This includes all shots in the paint area including both inside and outside the restricted area:
Kenyon Martin: 64-108(59%)
Ben Wallace: 28-64 (44%)
Darko Milicic: 58-124 (47%)
Chris Anderson: 52-85 (61%)
Kenyon Martin and Chris Anderson are clearly the most efficient inside scorers of this quartet. Now on to defense:
Defensive stat (steals+blocks+charges)
Kenyon Martin: 2.10
Ben Wallace: 1.81
Darko Milicic: 1.17
Chris Anderson: 2.19
Alternate Win Score:
Kenyon Martin: 1.83
Ben Wallace: 2.24
Darko Milicic: 0.74
Chris Anderson: 3.25
Looking at all of the above Darko is clearly the weakest link. He's the weakest defender, the worse rebounder, and has the worst 'win score'.
Wallance is the second best rebouder and has a great win score, but he's a pretty major offensive liability.
That leaves Anderson and K-mart. K-Mart is more versatile offensive (better scoring rates outside the restricted area and from midrange) but Anderson is a better defender and rebounder. Honestly, I'd be thrilled with either!