Well, he has a point... Except for the - probably rare - occasion where you're playing two players and BOTH want to play Hot Head, otherwise having the same character twice is redundant, you'd get much better value out of spending the same money on a different character.
But, your money, your choice on how to spend it.
In the end, I have all 8 Giants - plus Scarlet Ninjini - and I can tell you it's hard to pick some over the others. I didn't even mention Tree Rex - partially since, because he comes with all forms of the game everybody should have him already - but he can kick butt, with his huge ground punches. Hot Head is disappointing from his light up perspective (only his head lights up, when logically you would think his hands would too), but from a gameplay perspective he's cool... His soul gem is a fun thing where he turns into a (slow) motorcycle, one attack shoots oil while the other shoots fire, and the fire can light the oil on fire! And I just found out OTHER fire-capable characters can light the oil too. Hot Dog certainly, I still want to try non-Fire characters with fire, like Spyro.
Thumpback's main attack is a HUGE swing of his anchor, covers a lot of ground, while his other attack is a belly flop slide which is also a dash move, a way to get around faster. And when he gets his third attack, it's a simple chomp, allowing you to get more specific when you have to.
Crusher is also big destruction, smashing his giant hammer around. When he gets it, plus the upgrade to control it (there's two, I wonder what the difference is), the boulder form is fun, it's like a controllable avalanche or something. In constant motion you can minimize damage received, while bulldozing enemies.
So, yeah, hard to choose.