Agree with what? Your questions are unclear to me.

I think McCain was an evil warmonger who also sold out to Trump, but he did sometimes show some ethics and finally did start opposing the Trump policies.

He deserves respect. Fuhrer Trump would not read a prepared statement by his staff and refused to keep flag at half mast at White House. He is a POS showing his childlikeness.

I have some respect for him. He remained a POW when he could have gotten out early because his father was an Admiral. I applaud him on not taking advantage of his position. However, nepotism was in full force when he got into the Naval Academy because he likely would not have been accepted. He did manage to garduate 3rd from last in his class and still manage to get a pilot slot (only the top few of the graduating class get pilot slots), so more nepotism. He wasn't a safe flyer and had crashed a plane prior to being shot down and captured.
His politics were iffy and he might have been a a reasonable GOP president instead of W back in 2000, but I have no doubt we would still be in a never ending war in Afghanistan after 11 Sep. He wouldn't have gone into Iraq because that was personal for W, but the housing crash would've still occurred regardless. The money poured into the military industrial complex wouldn't have been as much because Iraq wouldn't be a factor, but McCain would've still promoted military spending. Who knows, he might have found a different country to invade, but his position on torture might have saved us from all those horrible Abu Graib torture photos.
In the end, he was extremely fortunate because he was born at the right time to the right parents.

My respect for McCain nose-dived in 2008 when he a) kept pinhead Palin on the ticket and b) caved to the far-right radical elements of his party. End of the day, he proved to be no maverick when it mattered...

McCain was nowhere near the worst of the conservatives. Most of the time, he did have ethics. However if pressured he'd flip flop to get along with his fellow republicans.

When he ran for president and chose Palin as his running mate, in retrospect it makes me wonder just how long he had brain cancer.

The political system is not meant to divide our nation it is meant to make us work harder to be better.

McCain was someone you could agree to disagree with, someone with who you could disagree on most all policies but still respect as a person. How many Republicans left can I say that about. Off hand, I can't think of any.