My recommendation for BD User, if you want to get many merits, just keep using the Meta board. Historically, this is where merit sources spend most of their merits.
I wanted to know if that was true or not so I consulted DdmrDdmr's
Merit Dashboard & these are the top 10 most merited subsections of the forum since the inception of the merit system:
Economics - 13.45% of total merit
Marketplace - 12.12%
Meta - 9.54%
Russian - 7.75%
Dev & Tech Discussion - 6.87%
Bitcoin Discussion - 6.18%
Trading Discussion - 5.43%
Beginners & Help - 4.28%
German - 3.93%
Turkish - 3.53%
So Meta is actually the 3rd largest subsection for merits -- whether or not it is more popular than this among merit sources, I'm not totally certain.