One reason leasing property appeals to me, is because once you buy a piece of land, a lot of different factors that you cannot control can come into play. Primarily, tresspassing and lousy neighbors. You won't know for certain just what type situation you will have, until you buy it and own it awhile.
If you're lucky, you could end up with a real gem of a piece of land. If you're unlucky, you can wish you never bought it.
I know a fellow who finally owns his dream property of around 120 acres. It is a beautiful piece of property that he has invested a lot of time and effort in with creating ideal deer habitat. The locals have recognized how nice a place it is also, and he spends quite a bit of time running over there late at night trying to catch tresspassers. He's even actually managed to catch a few and have them prosecuted by the game warden.
Me? I lease property from a paper company, and if the property turns sour for whatever reason and things get out of control there, I can simply look for another lease quickly for next season, without worrying about having to sell.
I guess in a way it's 6 of one and half a dozen of another. My experience is that I never know for certain what I have till I give a piece of property a try, and either way it costs money.
As for how many acres you need? Well my advice is buy as many as you can afford. If you've only got 50, you'll invariably see deer right across the line. If you've got 100, you'll see deer right across the line too. You get the picture.
In any event, you would need several thousand acres in order to manage your deer effectively, so with only several hundred acres or less, if you pass up deer to let them get older, the likelyhood of your neighbors taking those deer is very likely. Most people cannot afford to buy enough land to effectively manage thier deer, but large leases are possible.
If you can gather enough info on a piece of property you are interested in, a 50 to 80 acre parcel could turn out to produce some very good hunting if you get lucky and get one of those parcels. It's hard to know for certain. If you could lease with an option to buy, you could get an idea of what you are getting yourself into before you commit. Good luck.