Nice variety
Great variety! And nice proportions and balance 
However I don’t quite get who’s the one on the very left. I assume man based on the hips? But the rest of the body is a bit disproportionate IMO.
Yes, this guy at the left is quite uggly 
I tried to transform the base into a fat guy without great success
Nice collection.
Are they a bit head heavy?
Blockquote
Nice collection.
Are they a bit head heavy?
Yes they are. That is intended
Here the canvas I used:
Great, nothing wrong if intended. Looking good.
I don’t think calling any of the figures ugly makes sense in this context. Exploring anything outside of comfortable standards is always a challenge, and I appreciate that. I think if a man gained some weight, upper arm and upper thighs would be a bit bigger. If you make these adjustments, the left figure might make more sense.
The cartoonish style is excellent!
Long legs, the head all great models.
Regarding belly - I did sculpt of an orc/ogre and I know the extra weight on that part of the body it’s tricky to make. I did play a lot until I was happy with the outcome… I do like a lot the cartoonish skinny look with bigger heads 
you made me want to try play with the belly version as well, thanks