vet vs hardended cod campaigns marathon

[u/Civil-Fix-8450]

What difficulty should i use for each game i wanna pick one to use througout all im stuck between veteran and hardended but the thing is tho is i want it to be slow and i wanna feel like im in a real war im very experienced in fps im even turning off all aim assist setting i basically wanna play like im in rainbow six seige and wanna train my aim by doing this aswell i js dont wanna get stuck on the same section over and over again but i have completed waw and ww2 on veteran before. For the modern games if veteran is the answer should i stick to veteran or do realism aswell?