Worst ones are prolly the flags with Union Jack (Except for UK/Aus/NZ). Kinda lazy shit. Union Jack itself can be considered evil but not the worst thing aesthetically.

The story of how Canada avoided the "union jack in the corner" fate is actually really funny. The short version is that the minority-government prime minister of the time was about as anti-colonial as it was possible to get in mainstream 1960s Canadian politics and still be PM. He's the same guy who, as foreign minister in the 1950s, led worldwide diplomatic efforts against Britain in the Suez Canal crisis. He wanted to replace the old not-technically-official but official-ish British-as-can-be flag with something entirely domestic. He didn't want any European symbolism on it.

He and his progressive political allies basically tricked the pro-British conservatives on the flag selection committee into supporting a flag that he preferred, without any trace of the British symbolism that the conservatives demanded. But the conservatives didn't know he preferred it. They thought he wanted a different flag. They thought they were going to deadlock the selection committee by preventing a majority vote for any particular flag. The pro-British faction lost their shit when they found out that the progressives on the committee voted for the same new flag, making the committee decision unanimous.

The conservative opposition leader was one of those standard-issue North American anglophiles who never saw a British boot he didn't instinctively want to lick. He tried to filibuster the House of Commons to prevent a vote that would have made the new flag official, but some of his own party soon got sick of his shit and just wanted the whole debate out of the media once and for all. So influential opposition members rebelled against their own leader and forced an end to the filibuster.