As for merchants, yeah I suppose I could lean hard into trade, but I was wondering if it was worth it just picking the tradition and making a trade league without trade minmaxing.
I meant trade traditions when I was talking about a trade build. True, you can gear your empire way more towards trade than that
The trade policy is the best in the game, so if you're thinking about making a trade heavy build, sure, the policy alone is probably worth it already.
I'm not a trade expert though - I usually don't play that heavily into the trade mechanics, especially not as a megacorp, because I prefer the default subject types and civics. In my default game, I usually go for the marketplace of ideas policy, join a federation rather than form one, and produce consumer goods on my planets. Once I unlock ecumenopoleis, I dedicate one or two to consumer good production to feed my research worlds, and that's usually enough until I have like three different ringworlds full of scientists.
Also, I'm not that good in Stellaris, and I'm often rather vulnerable during the first 70 years of the game. A lot of people seem to think highly of consumer benefits, and since consumer goods tend to be one of my main weaknesses in the early midgame, I kind of see their point, but the extra influence is just too good to pass up. Now that I'm writing this sentence I'm noticing that the trade federation policy combines these two policies, so, yeah, I really think the policy is worth it.