actually, you don't NEED to match the tenses at all. the sentence can be broken down:

"I argued "

I is your subject

argued is your verb

the phrase '...that McD is/was/has been/will never be good for you.' is a 'noun phrase' and has it's own tense (so to speak)

it truly depends on waht you want to say:

I argued that McDonald's is good for you
I argued that McDonald's was good for you
I argued that McDonald's will never be good for you
I argued that McDonald's has been good for you
I argued that McDonald's hasn't been good for you
I argued that McDonald's is good for you

you see?