I somewhat agree on Demon's Souls. Many Bosses were very easy to cheese though, and i mean shoot thru a fog gate, get them stuck, poison without danger, easy but if you fought them legit i really did like the bosses in Demon's Souls the most. I disagree on the regen stuff. Demon's Souls by far had the most regen items and effects of any of the three games. Even if you remove the spell second chance and the absurd amount of grasses you could use, you had rings, shields and i believe even weapons that gave regen. I do think Demon's Souls has the best atmosphere. The world and character tendencies i find more of a hassle than a good feature. The glitches i mentioned above and also the item load system i found tedious. I still think its a fantastic game but its the one i least want to play of the three.
I don't blame anyone for having a completely different order than i do. Some factors are more important than others to the player. Its my favorite series and i look forward to any further soul type games they might make.
What I like about Demon's Souls over the Dark games (other than the atmosphere) was that the bosses (as you said, if fought legit) sometimes had a mechanic you really should/need to use to win.
Like the first boss, the big black blob. I was getting my ass handed to me repeatedly and was about to reroll a ranged character when I decided to try throwing fire bombs at it and voila! I kicked its ass.
So far all the bosses I've fought in DS2 are "dodge this, hit now".