I saw the first and second season back when someone uploaded it to youtube. The 2nd season had somewhat better animation and whenever Godzilla was swimming underwater he seamed to have less off model looking moments. his laser beams, human roars, and fire breath were off-putting to me at first but gradually I began to accept these things.
my favorite episodes were:
1: Micro-Godzilla where Godzilla shrunk, during his time at human size it was interesting to see how he disliked being small and how even captain majors realized it wasn't a good idea to get too close to him. The whole episode was interesting.
2: The city in the clouds had my favorite monster from this show, the power dragon, who actually sounds like an animal and was an ok fighter.
3: A tie between the episode with Axor and the Island of doom, Axor was possibly Godzilla's equal in combat in this show and it was astounding how much character he has, god complex and all. Plus, Godzooky even breathed fire! The island of doom perfectly showed just what would happen if HB Godzilla's allies were killed/captured, he could straight up murder an army if he had the mind to do so.
Besides those episodes, 3 individual moments caught my attention.
1: when the frios/ice people skreeonking FROZE GODZILLA!!!
You know they're a true threat when they can neutralize the king of the monsters so easily.
2: when the special torpedo form the German WW1 sub knocked Big G unconscious, the animation showing him on the ocean floor still bubbling and smoldering while zooky tried to wake him up was rather shocking.
3: During the penultimate episode when Godzilla managed to prevent tectonic plates from crushing him. Now that, is awesome.