I decided to run the scenario through my software to see what it says would be the best call options to purchase f you expect a relatively big move up in the next 3 days.
I chose to run it on the options of the SPY (currently at $150.15). For my target I said that it would go up between 2.5% and 5% (between 154 and 157.75) by October 30th (3 trading days from now). I also said to pick the best trade you can with $2,400 of capital (I chose that amount because you would need about that much to purchase just one December '09 150 (the ATM) call). I also told it i would not buy any options with an Asked price of less than 35 cents).
The results with the top 15 trade recommendations ranked by expected return are attached (note the third-to-the-last column which is labeled e.r., for expected return, based on your target projection coming to pass).
As you might expect for such a short-term trade, the top recommendations are all in the front month. Notice also that the top recommendation is the farthest OTM call in November costing 35 cents, and then simply goes down progressively by strike until you hit the ATM strike, when it then switches to the 2nd month out.
Using the same amount of capital for each trade allows you to easily make a direct comparison between each. Notice also the last column, p.p., which stands for probability of profit. The expected return may be larger if your prediction comes to pass, but statistically the probabilities are against you when you buy far OTM.