Yeah I'd have to go for Martin aswell , hands down.
Courtney was bad but not this bad.
While Ambrose , Morrison , Nehra , Nel are all horrible batsman they arent totally lost causes , they are all capable of hitting the odd boundary or contributing the odd 10 not out.
All of the others have what could be described as some sort of batting technique , when pressed they can play a legitimate forward defence & McGrath even swept Harbhajan for a couple of fours in India in 2001.
You will actually find that most of them were considered allrounders during their junior days , Craig McDermott & Mike Whitney were bunnies , but both used to bat in the middle order when they were my age.
The ultimate tribute to Martin's lack of ability came in 2001/02 when Fleming reasoned it better to declare 9 down than waste the time & have him walk out & take centre.
Dont think anyone who's seen him bat would doubt he's the worst .
Tests-
11 innings , 12 runs @1.71 , HS-7
ODI's-
5 innings , 6 runs @1.5 , HS-3
FC-
67 innings , 153 runs @3.64 , HS-25
List A-
23 innings , 37 runs @3.36 , HS-5*