On the account of 'which game is more scary' I believe DS1 was scarier, but so was DS2, just not as scary.
In DS1 you always had that 'chill' that something was around the corner, and if you weren't ready, that something would immediatly eat your face...literally on Impossible mode. The game was more 'Ok, that's f**king creepy' scary, like the nurse cutting into some poor guy before slitting her throat? That's just plain disturbing, and do I even have to mention Nicole's 'make us whole again' message when her face becomes a skull? *shivers*
DS2 on the other hand, tried (and succeeded in some places) to use gore and jump scares, it's was also more suspenseful than DS1, though most jump scares were cheap, well, apart from one.