The Shropshire Union, Staffs. & Worcs. and Trent and Mersey canals form a 'ring' of canals which can be covered in a week. The Grand Union Canal and the Leeds & Liverpool Canal have some fine scenery but wide locks which can be a bit daunting at first. The Ashby and the Lancaster canals have no locks, the Worcester and Birmingham has lots of locks, hills and tunnels! The Mon. & Brec. is isolated from the rest of the system but that makes it very peaceful. Don't forget that canals are a good way to see cities too, Chester, Warwick, Oxford and even London all look at their best when approached on the water!  If you are renting you'll need to consider the number of berths you require, the standard of accommodation and equipment you want, and the things that you want to see. Hills, castles, solitude, tourist attractions, museums… you have the freedom to choose. Closeness to the rest of your holiday locations may be a factor too.