They're very different instruments, create different sounds and are both as excellent as each other - plus there's a lot of subjectivity in terms of 'which one is better'.
In terms of difficulty, piano is definitely easier and reading the sheet music is also easy (from my experience) there's a lot of music sheets for piano, and there is a lot of history around it.
I guess if you're learning it, both instruments are rewarding. However, I think piano is more convenient since there's cheaper alternatives (i.e keyboard) to practice - and a lot of resources to learn from.