Fuchs make some very good oils, we sell a lot of them. They are good value for money as well as giving good performance. If you want top performance, go for Silkolene, who are owned by Fuchs.
Castrol make some good oils, but often they cost a lot for what they are. Castrol Magantec is very similar to the Fuchs XTR, but comes in smaller containers and costs more. Their strength is the Edge range which meet many manufacturer specifications as well as being good oils. They also produce some very good gear and diff oils as well as brake fluids.
Cheers
Tim