There are as many answers as underlying(s).
To clarify things for myself, I would answer:
1) How much of an unexpected pop am I desiring to cover? (What is a "sharp rise or tail event"?)
2) For how long am I looking to cover this risk? (And, How many expirations are available to me {with reasonable trading volumes}?)
3) Am I utilizing the taking of a (top-side) position with any eye towards flexibility? (I.e., buying a 2400 vertical versus buying a 2390 broken-wing, with a long front end, and a short back end)
The biggest things in the option (insurance) trade are distance from market, and distance from expiration. How you decide to work these two can be different for each underlying, each trader, and hell, each day.