Tomoe River 52 remains a top favourite - I have a couple of notebooks left, so should have it for a while. Have a couple of TR68 notebooks as well.
Cosmo Air Light is a close second - brings out ink properties beautifully and can take a lot of abuse.
The best value for money I've found though has been the Nakabayashi Logical Prime notebooks. The paper is fantastic, and the notebooks are priced decently.