Buy and hold

If you were allowed only to buy only 1 stock + put options for downside protection in that stock and be forced to hold it for at least 1 year from now what stock would you consider buying to achieve the best returns? 

I would never set up a trade like that with any stock. Being long put options for an entire year is crazy. In order to realize any positive return, you would need to make a profit on the stock that was greater than the premium you paid for the put option, plus any commissions and fees you incurred. US stock options expiry is monthly, so you would also have the inconvenience of remembering to roll the put option each time. 

Instead of buying put options as insurance, I would sell call options, with appropriately chosen strikes depending on the stock price each month. That is risky too, with negative upside exposure. 

If your intent is to buy and hold one stock, for an entire year, you are making a decision based on something that is driven by fundamentals of the company. Stay away from options. Buy a small cap company, of the sort that Mario Gabelli picks for his small cap growth fund (GABSX), see Mario Gabelli makes big bucks bucking trends. 

If you don't like that, do your research and find a company with publicly traded stock that is NOT on the Pink Sheets and has a high likelihood of growth or a massive one-time dividend (I'm thinking of Apple, just as an example) due to accounting or regulatory circumstances.

See what Dick Karp is up to at the moment. He is Quora's very own activist investor, and writes about his adventures here: I wanna be an activist shareholder! Jump on his coattails if you can. He has a good track record, for what that is worth. He also has deep subject matter knowledge in communications technology, which consistently helps him in identifying undervalued companies in that field. 

*A stable company with a decent dividend doesn't sound exciting but it is a good choice, see Charles Graybell's answer to this same question.