Only player I remotely consider over Buch from that list is Tkachuk.
And, as previously mentioned, I'd hang on to Buch for a bit to see how his usage is changed with Kreider out indefinitely.
Galchenyuk won't be fantasy relevent unless he's traded, the coaches in Montréal refuse to use him at center where he was most productive.
Steen is probably good for another 20 pts this half of the season. But his usage is up in the air once Schwartz comes back towards the end of the month. If dropped to the 3rd line his production will disappear - St Louis doesn't get much scoring from their 3rd line, great defensive play but not offense.