Well, i have not tried the ones you mentioned above, but I did have some old Princo left. Now, those are notoriously bad media and I got some great results (relatively speaking) with them.
Besides those, I tried TDK 16x (1.3 standard) TDK003 media - they were really nice as well. Very good quality burns.
I have bought some verbatim, but not yet tested those. I can post and let you know.
Just to try, get some princo -r 8x and give a whirl - I did not have one fail, and burnt all at 8x.
I know poeple will post and say they are rubbish, but at least you can get an idea if you should rma the drive or not.
To try a good disk, I would say verbatim (i like +r) 16x.
PS. Please post updates.