Just to throw in my two cents.
I measure each of the 3 strategies I trade separately and watch how they trend over time. (I want to see quickly when a strategy stops working) I measure my combo positions as a single trade (so, let's say I was doing gamma scalping, the starting straddle/strangle and all of the subsequent adjustments I make counts as a single position, not many).
This year, I've had 1134 legs, but only 363 combos.
Overall, I track:
1) Net results per underlying. I love to trade ENER, but it's so far one of my bigger losers with a win percentage of 67%, but a profit factor of only .79. This stat makes me more "suspicious" of the underlyings I consistently call or manage incorrectly (and more confident in the ones I consistently call correctly). TTWO, on the other hand, has a win% of 57% and a profit factor of 3.56.
2) Win/loss percentage per strategy combined with average winner size and average loser size. For example, my earnings long plays (i.e. I'm expecting a big pop, and I buy an option right before earnings), I'm only correct 29% of the time, but my average winner is 4x larger than my average loser.
3) Results per day. I graph Open P&L, Closed P&L, and Net P&L for the entire year. This allows me to see how volatile my equity curve is and reminds me to "take some off the table" if my Open P&L is dramatically higher than my Net P&L.
Sharpe ratios are more sophisticated and will give you good insight into your overall macro trading results. I prefer seeing my micro results--
1) Am I doing better or worse at a particular strategy than I was before?
2) Are particular underlyings troublesome (or good) for me?
3) Am I leaving too much or too little on the table?