I think both drugs are emotionally opening, even though they have major differences. Regarding physical effects I'm mostly talking about side-effects like jaw clench, unwanted stimulation, cardiovascular push, appetite loss, and of course all the after effects. Pretty much all are worse on MDMA IMO.
What is best depends on the person and what they are looking for. My own preferences are for 2C-T-2, 2C-E and 2C-P. I also have a special love for 2C-I. All of these are rather less beginner-friendly than 2C-B though.
Well it's all relative. I mean 2C-B and 2C-I are definite more similar to each other than to things like MDMA, LSD, or psilocybin. However, they also feel quite different to me. Compared to 2C-I, I find 2C-B to be warmer, more emotional/empathogenic, less mentally pushy, less stimulating, less visual, and a bit less euphoric. I think each is suited to somewhat different circumstances.
You make an important point. It could be said that MDMA is a lot more gregarious---it's easier to be emotionally open with strangers. With 2C-B those boundaries may remain in place, but in familiar company one can maybe go deeper and maybe more more sincerely than with MDMA.