This is a very difficult question because everyone has a different idea about what makes a suitable vessel for a circumnavigation. Classic literature used to suggest that distance cruisers needed to have 3 to 6 long tons of displacement of displacemnt per person when fully loaded. That translated to a boat between 25 and 35 feet in length. Today with better hardware, engineering and construction techniques. I would say that the boats have probably gotten a little bigger.
People have single-handed around the world in boats as small as the 22 foot Trekka, 23 foot Serifyn or 25 foot Folkboat derivatives, on up to 60 foot ultra-light race boats.
If I were planning such a trip I would probably aim at a 35 to 38 foot boat with a design weight around 10,000-12,000 lbs and an all up weight around 15,000. While a 32 footer (of 10,000- 12,000 lbs) is probably better if you are ''island hopping'' because smaller boats are easier to handle and easier to get into shallow ports. The bigger boats are much better for long legs and a ''globe trotting''type circum-navigation. I would probably use a fiberglass boat because tehy are more readily available at a realistic price but would beef the boat up. I would probably go with a fin keel and skeg hung rudder of moderate draft (5 or so feet, perhaps less for island hopping, more for globe trotting.)
Tankage and storage becomes important for distance cruising, which of course is a little dependent on your route, equipment and boatspeed. A faster boat in theory needs less supplies because they make quicker passages. Of course if you are cruising to some remote corner of the world you obviously need to have more ''stuff''. Equipment like water makers can also reduce water tankage size at the price of needing more fuel tankage.
You can buy and equip a world cruiser for as little as $20,000 US to, well the price tag in umnlimited but it would not be hard to spend $400,000 or more on a purpose built custom globe trotter from a first class yard.
I would suspect that most circumnavigators these days have boats worth somewhere between $100,000 and $200,000.
I don''t know if this is what you had in mind by your question. If not, please be more specific.