I will be byuing some new paper charts in the near future. There are 2 or 3 different types (Imray etc). Price is very similar; Is there any difference in quality? Any advantages and disadvantages?
difference in quality - Yes, paper quality used and amount of detail displayed are the things that immediately spring to mind.
The 'new' Hydrographics portfolio are much more akin to the others and IMO they are inferior, (mainly poor paper quality) but you should compare them for the area you want covered.
See how easy you can pick out details, read lat/long and compare one against another.
Which have the better embedded chartlets tidal diamonds and nav info.
When were they published.
Do you want folded or not.
Waterproof or not.
You DON'T have to have a 'matching set' some 'makes' are better for a given area than others and vica-verca for a different area.
A lot of it is personal preference. A quick inspection of the charts should give a good idea of the strengths and weaknesses of each.
The admiralty charts are undoubtedly the most detailed - but much of that is not really necessary for small boat owners. However they also tend to work out more expensive - although on a per-chart basis the Admiralty charts are much the same price as the others - you will probably find you need more of them since they omit information from the smaller scale charts where it is covered by a larger scale one - so an area that may be covered by a single Stanfords/Imray may require 3 or 4 admiralty.
My current favourites are the Stanfords series - I like the presentation and they are very durable.