The Green rhino is a great Tube Screamer; If a flexible screamer is what you want, get that.
Never actually played a Golden Cello - but have watched a bunch of vids. It is definitely a different take. If you think the delay will be a set & forget easy bonus, go for it. Honestly, I have mostly seen this thing used to cop Eric Johnson tones with one box. Not saying it might not be more flexible than that, and it does sound great.
Rhno: The best Screamer
Cello: The most fun
That's how I see them.
Note: I have a digital Metalizer, which is the BOSS HM/DD version of the same kinda thing. It is fun and simple...but I prefer my favorite delay settings.