The warblade on average forces 2.7 saves
The Warspear on average forces 2 saves
The Greatblade on average forces 1 save
This means they do the following damage on average against each save:
- save: -:
- Warblade: 2.7
- Warspear & Greatblade: 2
- save: 6+
- Warblade: 2.25
- Warspear & Greatblade: 2
- Save: 5+
- Warblade: 1.8
- Warspear & greatblade: 1.6
- Save: 4+
- Warblade: 1.35
- Warspear & greatblade: 1.33
- Save 3+
- Warblade: 0.9
- Warspear & greatblade: 1
- Save 2+:
- Warblade: 0.45
- Warspear & greatblade: 0.66
- Save 1+ (assuming natural 1's do succeed)
- Warblade 0
- Warpsear & greatblade: 0.33
As you can see the warblade does slightly more damage in most situations and the warspear and greatblade do the same.
However; the warspear will have the "smoothest" result thanks to having the highest rend and the highest attacks. As such it'l average out the quickest and is less likely to completly fail (or to do maximum damage)
The greatblade is most likely to be on the extreme's as it has the least amount of attacks. So it's most likelyto either do nothing, or do 6 damage.
The Warblade, like the warspear, will be relativly smooth in terms of forced saves. But due to the lack of rend it's more likely to stumble there.
Anyways overall:
Warblade if you want the best average, and don't absolutly need the rend
Warspear if you want the smoothest damage output
Greatblade if you want the spikiest damage output