Originally Posted by
noglider
There are too many to list, but my favorite might be the Raleigh International of the 1970's. Lots of Raleighs are nice.
The OP has to be careful of Raleighs from the mid-70's and prior, particularly the UK built ones. They have proprietary threading for the bottom brackets and steerers and compatible components are getting hard to find. I believe the "Raleigh Internationals" have English threading but be sure of what you buy.
As to Japanese bikes from the 80's and 90's, I certainly agree they make a very good basis for restoring, modernizing or customizing. They are generally well made and take conventional and readily available parts. Many are quite cheap but some have gotten pricey (Bridgestones in particular) as they have collectors value. Older Trek frames are also a good start.