I normally use the Atom editor, and since BE BASIC is a bit different from other BASIC flavours out there, I created a language package to use with it:
https://atom.io/packages/language-bebasic
The repo is here:
https://github.com/damianvila/language-bebasic
It's nothing fancy, and it may be missing a few things here and there, so if you want to contribute, feel free.
I hope you find it useful.