Flutes and pipes and fiddles etc can be amazing on the concert stage or other formal setting for short periods but it's hard to accompany your singing with them! in a lively crowd, for me, to communicate with the 'folk' as I define them, the 'best' instrument is the melodeon.

I have never played the melodeon but I do play the anglo concertina and they would seem, to me, to have the same problem as far as accompanying yourself singing. As each button gives different notes on push and pull, I find it difficult to control my breathing if I want to sing out long and strong when pulling instead of pushing. This limits my repertoire, so I only perform with the concertina now and again.

DC