Mine (since I was 5) is "My Hope is Built on Nothing Less" -- author, Edward Mote, 1834; composer, John Stainer (1873), #370 in the 1941 Lutheran Hymnal. Why is it my favorite? Because it tells me everything I need to know.

https://www.youtube.com/watch?v=dD97wzxr0xQ

My hope is built on nothing less
Than Jesus Christ, my righteousness;
I dare not trust the sweetest frame,
But wholly lean on Jesus’ name.

Chorus:
On Christ, the solid Rock, I stand;
All other ground is sinking sand.

When darkness veils His lovely face,
I rest on His unchanging grace;
In every high and stormy gale,
My anchor holds within the veil.

His oath, His covenant, His blood,
Support me in the 'whelming flood;
When all around my soul gives way,
He then is all my hope and stay.

When He shall come with trumpet sound,
Oh, may I then in Him be found;
In Him, my righteousness, alone,
Faultless to stand before the throne.