The point of this topic was to address your second criterion. While you have said unit X's focus is Y, it doesn't mean that's the only thing they do.
I want to be able to succeed in any environment: cold or hot, sea or land, jungle or mountains, etc. As far as missions go, I'm interested in SR,DA, and CT. I like learning multiple languages and cultures (I also have an interest in Intel).
Each SOF satisfies different criterion in different stages.
- Army SF are excellent on land, and are fluent in a second language. While FID is their focus, they still do above missions.
- MARSOC has critical skills operators that have intel-specific courses. Second language training is growing, but not required. I'm not sure of their mission focus, but are capable of any type of mission,
- Navy SEALs do SR,DA and CT. Can do maritime or land missions (obviously). Second language not required.
And yes, I want to get this right the first time, it's why I've been reading this forum, among others. My choice in a few months will define my life for the next half decade, at the least.