Is this the one you had?
https://www.amazon.com/Lionel-...sounds/dp/B017GUMBRQ
I believe it had a guitar version of silent night, I think possibly performed by Neil Young?
There are a few others that come to mind like the caboose Nick mentioned, but they are more TMCC dependent (though may work in conventional, just with less control of sound), I believe.
There was a Reefer that Played Frosty the Snowman, and I think another Boxcar, but I can't find a link at the moment.
There were a bunch of other battery powered ones, but those pretty much just play all the time when turned on, I think. (My opinion only, but I would not classify them as "best", which is what you asked. )
-Dave