If it is a certified aircraft then "The Aviation Consumer" contains a wealth of knowledge across a large number of types. None of the costs are relevent to the UK - especially post Part M but the accident record, mods, Ads etc are all gathered together - there is simply nothing elese even vaguely comparable.
THe key though is to first work out why you want an aircraft and what you are realistically going to do with it (by realistically start with what you presently do - grand plans tend to remain grand plans and buying an aircraft which fits the gerand plan usually means it does not suit the remaining 99% of its ownership period!).
That leads you to a aircraft usage pattern and then you need to identify the potential types which might fit that. If you use the experience of this forum do try and be specific - otherwise the suggestions will be useless.
After that most of the stuff above kicks in.