Since it seems this has been revived, I'll give my thoughts.
As someone who learned about BIONICLE's lore through the comics and the novels before ever seeing the movies, Makuta was always a perfect villain in my eyes. He was smart enough to fool everybody - multiple times - that he'd been destroyed or cast away, only to still be lurking nearby, waiting for the next step in his master plan to unfold. He was resourceful enough to never be caught completely off guard, and he always had a contingency plan in place. And he was evil enough to fool and corrupt and lie to just about anybody he deemed either a useful tool or in his way.
The way Teridax was written by Greg Farshtey was my second favorite portrayal, and my first favorite was (if this can even count) his appearance in MNOG. In the latter he came across as a truly demon-like being, untouchable and in a void state of nothingness (as he himself even claims) and smarter than any could comprehend. His dialogue of course was what made him in that game.
My very first true look into the character was through "Makuta's Guide to the Universe", written by Greg Farshtey. For those who don't know, this was basically a comprehensive guide to the Matoran Universe's most important happenings, accompanied by excerpts from BIONICLE novels and "diary entries" from Teridax himself. Reading "his thoughts" further solidified my opinion that this dude was evil and awesome, and purely unbeatable. Until of course he was crushed, in the end, by destiny.
So, I like him. I like his character and his personality. His name I'm okay with, but it doesn't really communicate his evil; not like a name such as "Sauron" or "Morgoth". Like many I would've preferred his name to stay a secret.
His portrayal in the movies was... pretty yuck, in my opinion. He came across as merely a greedy thug in my eyes. Which I guess he is no matter what, but in the movies that's sort of all he was. So I didn't much care for that. And speaking of things I didn't care for (and going off-topic a bit), I kind of preferred believing he was actually brother to Mata Nui then knowing he was only one of a species - of which he wasn't even really the most powerful. If he'd actually been related to Mata Nui instead of being one of the creations, it would've made the character's entire arc that much more emotional - and evil.
But otherwise, I think Teridax is a very capable and cool villain; not the best out there nor my favorite, but definitely great. It was during the early years when his origins and appearance were still mostly unknown that he was the most malevolent, in my opinion. But he's a pretty fly baddie all around.
And I definitely agree with all you have to say here, Esquire.