If you liked the first one more, then by all means do not watch the third one at any point in your life.
Even looking back at Heath Ledger's performance now, it's really iconic to me at least, and I really don't know how to put it into words to explain it to some who would say otherwise. It really was unique performance you wouldn't have found in any movie back then, and I don't feel as though time has changed that yet if it would ever.
Then again, I do understand if you would say it doesn't look like how much people praise it to be. Like all things really good, when language is used to express how good you feel about something, it can seem like an extreme in contrast to what you mean, language can be pretty limiting at times. For example, to say masterpiece is also very relative and comparative. Though using the word "perfect" would be wrong, again, that's how a lot of people would describe something they really really liked.