imo neither are anything like lsd. Although i do really enjoy both of them. not much of a headspace i usually wanna talk more than sit around and think. Its decently visual when I take like 2mg of 25i but in general is to me its barely visual at all compared to real lsd. I get a decent amount of empathy from 25i as well. It also lasts about half the time of lsd.
If you are aiming for a lsd replacement I think you will be very disappointed. I was in that department but have grown to really like it in the end as it is really nice to go out and be social and dance on it.
25b imo is more like lsd than either 25c or 25i.