I think you are being unnecessarily impatient. We can help you find the cheapest flight (if we knew exact dates), or the shortest connection, or the longest one (for most miles), or the one that employs/avoids a specific connecting city, etc...but to declare something to be the best, you need preferences, and for that you need experience, of which you seem to have very little at present.

For example, how many 15-hour non-stop flights have you flown? If none, you can't know if you'd love it or hate it.

How many times have you connected in London, Frankfurt, Amman, or Singapore? If none or very few you can't know which one you'd choose and which one you'd want to avoid, for whatever reason.

As someone who is just becoming aware of FF programs, you can't possibly know if you would really like to fly extra (eg, DEL-FRA-LAX-NYC instead of DEL-FRA-NYC) just to earn more miles, as some in this forum love to do?

It takes experience to discover all this about yourself and you can't substitute theoretical thinking for that.