I struggled with the same choice (I'm 6'2-3"), experimented with bamboo sticks I had laying around. Was tempted to ask the folks at Fly Tyers Carry All to make a custom length in between (they will). Finally went with the 59" and am glad I did. It's a bit too long as a long-journey hiking stick (arm would be too elevated), but is perfect for the stream. Very often I put it ahead in a hole that is lower than my current footing, and it is helpful to pull myself up with when climbing a bolder or log.

Plan on getting one o' those "fly retrievers" for it too, and the extra length will help.

If you can get out into a stream before you order it, take/get a stick or 2 that are exactly the target lengths.

Don't forget to pick up a rubber foot.