Halo 3 managed to do what Halo 5: Guardians can’t (as far as the beta). Halo 5 has bullet magnetism and aim assist. I can understand why aim assist would be in Halo 5, due to the slower movement speeds of analog sticks, but I can’t justify bullet magnetism. Halo 3, albeit having noticeable aim assist, didn’t have bullet magnetism. Why? Because the developers of Halo 3 didn’t ask “How do we make this game easier for consumers”. Instead, they asked “How can we make this game fun and fair”. Halo 3 managed to be very fun while not having armor abilities, sprint, dodge boosters and etc. Statistics actually show that the Halo 3 Beta had 6 times the hours spent than Halo 5’s beta.
tl;dr: Halo 3 is superior to Halo 5.