They are both great soaps for not much money - don't deny yourself the pleasure - get them both. Life is too short not to have good shaving soaps.
The only thing I don't love about Cella is the jar. It's got such a tight radius that it is a little more challenging to load, and I'd like to have a little more room to twirl around. That said, it has given me a top-notch shave every single time and it seems to last forever. I also don't have anything bad to say about Proraso Green, and for my taste has the perfect amount of menthol, enough to numb you a little but not too much. What I haven't tried is Cella aftershave. If I "had" to choose between the two, I'd first want to test Cella AS & see how much I like that versus Proraso AS, which I absolutely love. That would probably be my tie-breaker, as I like to complement my lather with the right AS -- it doesn't have to be same brand or scent but it has to match well and I love Proraso Green AS with the soap . Luckily I don't have to make these choices and I can enjoy both!
Agree - the container is a bit small. I use a bowl to create my lather so I just load the brush from the container and go to the bowl.
In my collection of Shaving Soaps I have both of these soaps. I prefer over both of them my Van der Hagen-Williams Shaving Soap aka Patrick's Blend.
Cella gives me less skin irritation than Proraso Green, so that's an easy choice. In reality I would choose neither though.
I've used both and they're decent soaps. I prefer Cella. Did you settle on these two because they're Italian soaps? If so, you might want to also consider Linea Intenso -- Tcheon Fung Sing, which I prefer to both those soaps. Just a thought.
Two excellent soaps. Get both. As much as I love Proraso green I would give Cella a slight edge for slickness.
Yes, this is the only true answer to this question. They are both economical and have knockout performance and smell great No reason to over-think this by trying to choose between them.