A toss up for me. Scanlines are for nostalgia and in my opinion, make Amiga graphics look more defined and less blocky. No Scanlines give you more clarity a much more consistent look but make things look a little blocky. \
But i know i never had any complaints when i was using my Philips monitor .. loved the damn thing until it blew up.
I don't know, maybe thats just my stupid brain making those observations that aren't really there ?.. but thats how i see it.