In a manga, an ego for a character can be developed by emphasizing their skills, achievements, or the way they are perceived by others. It could also come from their own self-reflection and changing perspectives over time.
It's a bit hard to say for sure. Both Vegeta and Goku have their moments of strength. Goku has some unique powers and techniques that give him an edge at times, but Vegeta is no slouch either and constantly works to catch up and surpass Goku.
Generally, Goku still holds the edge over Vegeta. Their power levels fluctuate, but Goku often achieves higher peaks of strength and unlocks more powerful forms first.
You could try 'My Hero Academia'. It shares the theme of heroes and powers, and has a dynamic art style like Ultra Heaven. Plus, the character development is quite engaging.