Wow, there are a lot of first world problems here.
I do find it strange that the OP can't use the GPU to upgrade from J to F -- it is extremely rare that I see ON == 0 on any flight I take, although admittedly I book TPAC and not TATL.
That being said, if the choice is UA F or LH F, it's LH F every single time.
I also cringe at the notion regarding "If you ain't GS...." I am understandably curious: as an almost 10 year 1K, with the last 5 out of SFO, just what indignities has the OP really suffered? Not UG on TCONs? Buy F if you want F, but it's nothing to do with being in SFO, it's everything to do with the competition for less seats on the "ps" product. the reason you see all the GS up front is they mostly buy up front, otherwise they wouldn't be GS because they didn't spend as much. Correlation is not causality.
As a 1K, I am routinely upgraded on the short hops up and down the west coast -- as the OP is as well -- even on rock-bottom fares.
As a 1K, my interactions with reservation agents have been mostly good. Can think of only one terrible one in my years of calling. I firmly believe they have been mostly good because I take the time out to ask how they are doing by name at the beginning of the call. I suggest everybody try it -- you will hear a distinct change in their voice to a much happier spectrum.
I'll ask again, what's so "bad" about being a 1K out of SFO?
Back to the spirit of FT -- what should a 1K (or a 1P, for that matter) do when they reach status and can't get to the next level? There are two choices:
1. Don't waste status and fly somebody else. This mainly works only if you have status on another airline, particularly if one is feeling aggrieved with one's main airline. It is unlikely that Joe Q. Public will be treated any better than an elite. But it is worth a test to see if the grass really is greener -- toward a shift in "loyalty".
2. Keep on flying and enjoy the perks of the status. I will add here a rhetorical question: what is the point of achieving status if one does not plan to use the benefits (tangible or not) of said status? I get it that GPU/RPU are hard, but they are far from the only benefits of 1K. Free bags. Much shorter lines in airport. Almost always guaranteed overhead space. Free snack. ...
To actually be constructive: Given the OP flies TATL on LH, and is purchasing LH J, then perhaps the OP should look into Miles@More? Would the OP travel be enough to chase SEN? Is that better than 1K, given the OP flying patterns? It grants lounge access for the TCONs, and I thought better access to LH/LX F awards.