I suppose I should discuss what size of boat I would like.
Well, the upper limit is set by mooring limits in the harbour I'm thinking of mooring the boat. With 25ft being an upper limit before mooring fees step up significantly. However price factors highly here and a realistic affordable length limit is around 22ft.
The majority of boats in my miserly price range are between 17 and 19 feet in length, so the odds are I'll buy something in that range.
Another factor to consider with a bigger boat is increased maintenance costs: more paint, more rigging, bigger sails.... just more cost.
So, 17-20ft it will be. Plenty in that range: Caprices, Hurleys of various flavours, Leisures, Newbridges, Proctors, Sea Wych's (not my favourite), Vivacitys, Valliants......