A "sub" with a 6-1/2" driver and likely less than 100W RMS isn't going to do much subwoofering in a 16' x 16' room. So, IMO, go with any of the ones that fit your budget. They'll all give you roughly the same performance.
-- Edit --
I just checked the subs' power ratings and I stand corrected: The Mirage MM-6 has a 200W RMS amp.
I took a quick look at the other subs' product pages and owner's manuals and I didn't see any mention of RMS in the power ratings:
- Pinnacle SUBcompact6 - 200W
- Pinnacle SubSonic - 350W
- CA Minx x200 - 200W
So, I'd go with the Mirage sub.
-- Edit --
I just checked the subs' power ratings and I stand corrected: The Mirage MM-6 has a 200W RMS amp.
I took a quick look at the other subs' product pages and owner's manuals and I didn't see any mention of RMS in the power ratings:
- Pinnacle SUBcompact6 - 200W
- Pinnacle SubSonic - 350W
- CA Minx x200 - 200W
So, I'd go with the Mirage sub.
