Outside of technical, from a business standpoint it is strictly working with a standard.
You can find training for EJB/J2EE (plug Jboss Inc's own training here). Can you for the other frameworks?
The availability of experienced skilled people for EJB/J2EE is much higher than the other frameworks. Along the same lines, you can get certification in EJB/J2EE that you can not with other frameworks (if you consider certification of value).
And future itself...well, if you have a mass-market usage such as EJB/J2EE, it's future is pretty stable. The other frameworks I'm not so familiar with their 'mass-market' and future stability.
anyway, that's two coppers to the pot.
I'm not doubting JBoss or EJBs market penetration, they are well respected through-out the industry. I was looking for the reality of the need for EJBs, as most frameworks offer features that "seem" to make EJBs obsolete.
Now where I say seem, I'm wanting to know what problems and/or design do you hit, where you see no other option but to use EJBs?
EJB3 makes the existing heavy weight and non-standard lightweight mechanisms obsolete as it focuses on a pojo based model. Its the direction jboss has been moving for over a year now.