dude. Obviously HCMC is better. You're officially required to use HCMC. If you apply through Ha Noi while in Da Nang, your application could be rejected or cancelled.
As for which is better aside from that.. they're going to be about the same.
When I went through, I gave the lady my passport and printed visa paper. The didn't say a word, just grabbed the DTV stamper and stamped. It's that way for nearly everyone
Anonymous participant 117 right.. so using his sketchy business on top of the overstay would be more likely to be rejected compared to a soft power activity where he already paid someone in Thailand. Though maybe he still could get rejected on soft power and lose the class tuition also