When I was in my "heroic dose" LSD phase, I never experienced any kind of leveling off at higher doses. My standard dose was around 800-1000ug, and I usually went 4-6 weeks between the big ones for integration, and to prevent a buildup of tolerance. When I went above 1000, it got correspondingly stronger in a more or less linear manner. At 1600ug I had a hard time bringing back anything useful, so I never went above 1200 after that except in one occasion.

That week my wife and I went to Florida to drop acid and hang at the Dali museum for a few days. I brought a big fistful of double dipped paper and we were taking it twice a day. By the last day, I took 1600ug and could barely feel any effects at all. So it's really true that you can quickly develop a radical tolerance in a short period.

DMT and shrooms are my only experiences and they both felt very "Dream-Like". Is there less of that sensation generally in an LSD trip? I just can't imagine it not being dreamy.

Very "slight" aspect of dreaminess for LSD, but totally overridden by this "electric" high energy quality that only seems to be present with LSD..

LSD is in no way shape or form "more intense" than shrooms. All psychedelics are equally intense in their respective dosages. The only one that differs ime is dmt, which has an INTENSE body high even when no visuals are present. Some people even get turned off by that and are afraid to go further. Aside from that I think the only reason it's regarded as more intense is because the vaporization method has a quick onset. As for shrooms vs LSD vs phens (only one ime is 2c-b) the differences are extremely subjective and IMO mostly placebo. There are some distinct characteristics in headspace and visuals, but the whole "LSD is the drivers seat, shrooms is the passenger seat" has never held true for me. Both substances can give me a royal butt kicking when they want to.

In terms of visuals and headspace, I find LSD and phens to have similar visuals and LSD and shrooms to have similar headspace. Phens almost feel completely lucid at times. As for the visuals, I find tryptamines to be much more engaging and posses a sense of divine order behind them. LSD and phens really just make my world look like a bad Picasso. Its less of a main focus and more of a side effect of tripping in my opinion. Ive caught myself saying "eh the worlds melting, big deal" on LSD. But to be fair in higher doses some cool stuff dose happen. I may have some subconscious bias against LSD since my first trip ended horribly.

Tl; dr
It's extremely subjective and the bulk of differences are paradoxically similar in a way that makes it difficult to properly distinguish in language. You really just have to try it to find out. If you can find real LSD go for it. If you come across dmt absolutely go for it. Ime it is the most unique psychedelic of the bunch

in my opinion dmt takes alot more mental preparations than lsd or shrooms. breaking through on a dmt trip is like nothing you will or have ever experienced in your life and it can be terrifying if you are not prepared or do not know how to handle it. lsd for me is not more intense than shrooms and ive taken high doses of both. to me the major differece is that lsd is a little more edgy and shrooms a little more controlable, but ive also heard the opposite from people. the only thing close to a bad trip on shrooms that ive had was when i took it with an maoi and that is only because the dose was WAY too high lol.

but seriously do your reasearch before anything so you know what to expect and just let go and have fun. all these wonderful substances can be teachers and mentors to our consciousness in their own ways!

Mushrooms and DMT.

For me nothing else compares, so it is hard for me to try to compare them.

Salvia is also just hard to compare to anything.

..though I have never tried iboga.

Just want to add to what dmateo said... I find that dmt is one of the hardests to prepare for before hand, but also one of the hardest to have a bad trip on. I think a lot of the fear comes from reading trip reports and the things everyone says but it's really a gentle drug once you get passed that awkward first hit. Everyone I've introduced it to has had a blast. But some who have come to me looking for it after years of research end up too terrified to try it.

Though every substance is unique, i find that it is very clear that some substances have more in common with eachother than others.
Salvia, iboga, amanita muscaria and DXM are substances that definately fall in a different category than the classic hallucinogens. They have very little in common with LSD or DMT.

LSD, mescaline, DMT and shrooms though, are clearly members of the same family. Within that family you can also make distinctions, and then mescaline is definately part of a different branch of the family tree then DMT is. The three most predominant branches within this family would be: tryptamines (DMT, shrooms), phenethylamines (mescaline, 2-C's)and lysergic's (LSD, morning glory seeds).

Shrooms can give you an experience that is equal to a DMT breakthrough. To me, those two substances (DMT and 4-HO-DMT) are by far the best of all of all of the classic hallucinogens and they would share the first place on my list of favorite entheogens, followed by mescaline at number two. Mescaline is definately capable of taking you to other worlds like DMT is, but it has a few downsides: you'll have to take a dose large enough to make you trip for more than 18 hours and it does get a bit foggy at larger doses (and it is also more expensive).