I really liked the show growing up, so I'm looking forward to seeing the finished product.
On the muscle debate, I believe that one of the main reasons Goliath, or any of the other gargoyles, didn't have any definition was that drawing that kind of detail would shoot the budget through the roof. I remember some making-of commentary on Disney's animated Tarzan movie, and what they pointed out was that Tarzan was a huge deal and still is, because he has muscle definition, and spends the majority of his time in a loincloth. Animating defined muscle well ranges from a huge hassle to impossible, depending on your budget. It's likely that they just took the easy route and made them less featured to spare expenses. It might also have helped to get what was basically permanently nude people past censors.
In the case of the muscle suit, you could cut back some on the bulk of the biceps and triceps and add some more to the core. The white walls behind you could be camouflaging the sides, but it looks like you have a rather thin waist at the moment.
Lowering the deltoids a bit could also work, as you seem to be getting "crowded" from the sides, allowing too little neck to show. Higher shoulders also take away from how broad you become, and in body language it signals tension and anxiety. Goliath's shoulders sits further down, implying he's collected and calm. Just an idea on how to get the silhouette.
I'd also like to see what it looks like from behind. All the gargoyles hold their legs horizontal when they fly. This means that they need ridiculous strength in their lower backs, especially since they don't seem strained at all and have huge, powerful legs.
On the feet; right now they look a little "boxy". His feet tappers backwards, so trimming off the sides towards the heel if possible could get you the look.
Are you planning on filling in the "valleys" in the pectorals, or have them like this? If you're going for a supercharged human physique, that kind of definition is very rare, and might even look strange if the rest of the body is less defined. The chest is an area where both bodybuilders and strongmen alike seem rather smooth, bar the valley down the center (which Goliath does lack as well)
Keep in mind that I have never built a bodysuit, and look at this through a lens of sculpture study, so what works might not transfer over. Grain of salt and all that.
Also, it's your suit, so you do what you feel is right.
As a last addition, I managed to find a series of closeups on one of the figurines of Goliath. It has some more detail to it, so maybe you can use it for inspiration.
https://www.flickr.com/photos/29246775@N04/sets/72157622359069991/show/
