Dental Implants Odor - Inevitable Consequence?

With good oral hygiene and plaque control, I don't think you need to worry about an odor issue. As far as implant brands go, today the major implant manufacturers all have good products and get good results. I like Astratech, Zimmer and Straumann.

Implant failure or success doesn't necessarily depend on the implant brand.  There are hundreds of implant companies.  Each doctor placing dental implants may be comfortable with a different implant system.  Success with implants depends mostly on the experience and skills of the doctor rather which implant brand they use.  The most important thing is for you to chose a doctor(s) with whom you feel comfortable to place and restore your dental implant.

To answer the second part of your question.  The gap junction is the connection between the dental implant and the abutment (post) which is microscopic and where it's believed sometimes bacteria may grow.  No implant system is immune from the gap junction.  Gap junction does not seem to be a major problem in implant dentistry.  The only way to avoid the gap junction is by placing a "one piece implant," where the implant and post are fused together and cannot be separated.

Microgap exists with every implant type and referrs to the junction between the implant platform and abutment (extension supporting the crown). However, this microgap does not accumulate plaque which is often the cause of odor. So it is not a concern from that standpoint. Current day implants and restoration techniques allow biologically compatible environment around the implant which are easily cleaned and maintained healthy.