Actually, deep in the money calls don't really beat just buying shares on margin (depending on values of "deep"). For example, ETrade's margin rate on TSLA is 40% currently. (Do all the brokers use the same margin rate for particular stocks? I don't actually know.)
So suppose I have $100k to invest in TSLA at close today. I can buy approximately 200 shares without margin, or 500 shares with margin. Note: 100% cash needed for options.
The point of "deep in the money" is that the option will move approximately dollar-for-dollar with the stock. I'm too inebriated to do deep research (that means spreadsheets) but here are some data points.
Jan 15 '21 $200 calls last trade was $288.05. So I could buy 3 of them (since they trade in 100-share lots), for $86,000 and still have cash left over. But that's fewer share-equivalents than just buying the stock. OK, need a higher strike.
(I actually do this. I decide how much I have to spend, then find options that fit my recipe. There are many variables. But let's keep using Jan 15 '21, since that is the first full-month date after the S&P inclusion.) I need to buy at least 5 contracts to beat just buying the stock on margin. (Have to look at bid-ask since many possibilities are not liquid.) $290 strike bid-ask is $198-202.65. So those are roughly equivalent to a $490ish stock price (strike plus option cost). The time value (theta) is only about $3.
So to get more leverage but still be wading-in-the-money, let's try $400 strike: last trade $106.90 (between bid and ask, quite liquid). I can get 9 of these, and the theta is about $10 per contract.
Time to cook dinner, but my takeaway (not a recommendation, just what is mostly working for me) is to go for close-to-at-the-money. You would be spending $52.5 for $500 strike, but expecting the stock to go up at least $60 in the next two months for this to pay off. It just went up $80 in two days...
So, over the past two days, a Jan 15 '21 $800 Call is up 147%. I think there have been other examples posted of similar out of the money calls up big over that time.
The question, I guess, is what you're trying to accomplish. So far, I've only wanted to put small amounts of money into options, and I'd rather get a handful of these far out of the money calls than at most one in or near the money call. On the one hand, I've had a couple expire worthless (including an $800 heading that way this Friday). On the other hand, the ones that don't expire worthless show pretty impressive returns.
I assume the advantage to in-the-money is a lesser loss if things don't go as planned, though Jan 15 '21 still doesn't leave a lot of time to react if the stock price tanks. I just can't convince myself to do it. If I feel conservative, I'll buy more shares. If I feel confident in an IV/stock price boost, I'd prefer the return on the out of the money calls. I haven't yet found the middle ground.