Until now I have tried four different PDF viewers on the T1, and none of them has satisfied me.
ezPDF: Although I really like this app and use it on my phone, it is absolutely unusable on an eink device. If there was an option to turn off all animations, it would probably be worth a try.
RepliGo: Animations are less annoying than with ezPDF, but its functionality seems to be very limited.
Orion: Was recommended in another thread, as it is one of the rare apps with support for the T1's page turn buttons. Plus, it doesn't animate the page turns. I personally like the manual crop feature, but autocrop is not (yet?) available. Might be a good choice for some very simple PDF documents, but that's all.
Original Sony Reader app: Probably the best available app for the moment, but its functionality could still be improved.
I gave up reading PDFs on my T1, and I can't recommend to anyone using this device as a PDF reader.