Quality matters. Cheap toilets don't do the job, but I spent a little extra for the best flush model and it flushes better than our old toilets.

That's exactly what I've said and done for years. I now even double-flush old toilets out of habit.

The older style toilets I remember as a kid just worked. One flush would properly and fully clear out anything that didn't clog the darned thing.

The new toilets barely flush properly with two flushes, and I still wonder how much is left behind in the backwash.

I had the opposite experience. Old huge tank toilets got clogged and the new high efficiency ones don't.

Exact opposite experience for me. The traditional toilets in my childhood home (mid-90s) were (still are) slow, took several flushes for solids, and clogged constantly. The modern low-flow toilet in my current home flushes quickly, never needs more than one flush and never clogs.

Anecdata is anecdata. It's most likely that some toilets are just bad and some are good, regardless of flow amount.

Water saving toilets came out (or just were mandated) in the 90s and quickly earned a bad reputation. Over time manufacturers have learned to make good toilets that use less water. Note that water savings in the 90s was a major savings over the toilets of before then, but is more than twice as much water as toilets today, even though good toilets today work better than the best of the 90s.

The modern ones are slightly asymmetrical, and give the water a spiral/swirl. Probably less bend internally also. And maybe teflon-like "anti-stick" coating.

Yeah I think we picked poorly (the plumber recommended this one). Maybe there's a valve we can tweak a bit somewhere, I should look into it.