Gurren Lagann? :3
but that doesnt have anywhere near as much power as the first one. basically, i want it to have a lot of weight, but still look powerful.
Actually, I disagree. I like your second one a lot! Big-O (and Evangelion and Gurren Lagann!) did things right where a lot of other giant robot anime fail, because the robots move and fall realistically slowly. People tend to think that since a giant robot is human shaped, it should tip over and land on its back in the same time it takes a human to fall over, which is obviously false. A person hits the ground in a second (or less) after tripping, but a giant robot's head has to travel hundreds of feet before it hits the ground...
Basically, your second one is refreshingly realistic, in my opinion. I'm sure there's a way you could make it look even better, but right now, you're really conveying a good sense of scale for your robot - I'd be able to tell he was huge even without the car there for reference, which is impressive.
Honestly, your first one looks a little silly if it's supposed to be a large robot. It's too quick and cartoony. Your robot has a great sense of weight in your revision, which is what a giant robot needs most, hahah. I wouldn't worry about too much about the "power" you mentioned - the second one looks like he'd easily crush a house!