Depends on what you like more. Euphona has a fair bit more raw damage and the ability to be built as a hybrid gun for both crit and status (which is really powerful). The balance is the projectile drop being worse than most bows, and the low ammo pool/slower fire rate.
However, Sicarus has a pretty good fire rate, accuracy, and status chance itself. Overall it is a little weaker, bit it’s faster. Only issue is the burst-fire and some people like that better so ya never know.
Try them both in earnest lol. Nothing bad comes from forming your own opinions.
With that in mind, WAIT to get Sicarus. It is coming back out of the vault in January and you could get it for really damn cheap if you just wait a bit.