LSD has a very good safety profile, but it has "only" been eaten for the last 60 years.
Mushrooms have been with us since the dawn of mankind. Although you probably realise the effects from mushrooms come from a chemical as well, just like LSD.
For me personally, LSD may be easier to dose, if you *know* the dose per blotter (as in, you had it tested, not someone told you). Anything under 125-150mcg will give you a very clean trip indeed, where dry mushrooms in the 2-3gr area will give you a trip of "similar" intensity (very hard to compare IMO), but there *may* be a bit more confusion during the comeup of mushrooms.
Again, for me personally, LSD is more of an "active" trip (you still do things) where mushrooms are more passive (put some music on and go into your own mind). All depending on dose of course and it's really impossible to predict how one of the two will affect you.
Also worth mentioning is, mushrooms is over after 6hours (sometimes 8, high dose), LSD after 8-10hours, (sometimes 12, high dose).