Q:

How should I write this passage to make it the most readable?

Been writing something and was wondering how I should notate these measures to ensure readability.
These three ideas are floating around in my head but if anyone else has input please send it my way.

A:

Certainly not the first.  The second is unobjectionable.  But why not the third?  It's the standard notation, and is just fine.

A:

I'd go with the second or the third, depending on the clef that you need before and after this passage.
The first one feels more uncomfortable that the others.

A:

I'd guess you're trying to improve readability by reducing the use of ledger lines? below or above? The thing is, the piano is an instrument which is notable for it's range (on paper, a wider range of pitches than a standard orchestra). So pianists have to handle these a lot, and most will be used to reading off either end of the score (depending on their level of ability).
I'd usually consider using 8va marks or changing clef if...

The entire passage is outside of the clef.
It's a repetition of a previous passage, moved up or down by an octave (I.E. so the score looks the same with the octave shift).
You've having to space the staves further apart to fit the stray notes in.
The pianist needs to literally sit in a different place to play the piece.

These are just guidelines, anyway. There's a judgement call to be made here.

Also worth considering, if your player is uncomfortable with this, you could try inverting the two notes in the right hand. With the repeating F at the bottom and the moving line played above it. (This would have the dual effect of making the moving notes act as the main melody. Which is probably better if it's a solo piano piece, but might steal attention if there's also a melodic instrument playing).

