There are no missing runes because the runes pre-date modern languages by 1,000 years or more. 24 is all you get. Rather, there are EXTRA characters in our modern alphabet that do not occur in rune script.
There is no absolute "best" rune, they're all good in one respect or another.
If you care to visit any of the websites linked at the bottom of this page you will learn all about the runes, their letter equivalents, how to transcribe messages into runes, and you can find the meaning of each rune and thus choose your own "best" one.
I'd just use the 'w' rune if you're intent on using the Elder Futhark. Otherwise, why not use the 'v' rune from the Medieval Futhark? It looks just like an elder (or medieval) 'f' rune with a dot placed between the main stave and the upper bistave.