Halo 1 and 3 I agree
Halo 2's legendary is just not fun, theres no skill involved at some points it's just luck. I did beat it on Legendary like 5 years ago but it was the second most unpleasant experience to all of Halo 5. Not just that but the Ultra spam and weird enemy placement just breaks immersion. Halo CE and 3 Legendarys till feels immersive, H2L just feels like bad fanfiction with its enemy placement and spawns