Do I have a legitimate legal defense if I choose Tennant B over Tennant A because of the "vibes" I got from each of the two if Tennant A decided to sue me for discriminatory tennant selection?

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A lot of CPAs have nation-wide practices without too much trouble though.

I acquired a 1-story office building early-2018 (that was occupancy-ready at the time of purchase) and am currently in the process of selectively demolishing 25% (non-structural) of the interior to make way for $700K of renovations (still to be used as an office building). 

You can't turn every tenant around but if your more selective with screening you can get a feel for people and find ones who will take care of things and appreciate your efforts. 

I selected the desk next to his, every morning I picked up an extra coffee and the daily news for him.  

You must be fully immersed in your selected markets.

I assume this targeted and professional approach helped immensely thus far.I don't claim to know everything or anything about this method since its my first time... and it was TEDIOUS the way I hand-selected everyone, however, people have only had my letters in their hands since Friday 4/22 and within 4 days, my response rate is 8%.

Know your selected market well and know it's best locations.  

Value add year 1 COCRs will vary widely.