I personally think that the Silkolene PRO oils are excellent and represent one of the best money can buy quality wise but Motul have come a long way in the last few years and are catching them fast. There's also Mobil1, still a great oil.
5w-40 and 10w-50 are good grades depending on application and use.
Cheers
Simon
http://www.opieoils.co.uk/lubricants.htm