I think both Technology and Marketing are essential.
Right now I am evaluating two projects. One has great tech but a small community and very little marketing. The other project has a larger community and fancy marketing materials but its underlying technology is not as strong.
Which project should I support? Is it easier to fix broken tech or implement an effective marketing plan?
I would say the small community with little marketing because that means you are getting in early and it has room to grow by starting there marketing and growing there community. Especially if you feel there tech is very strong.
The one with the larger community and has already marketed may already be at the peak of its growth especiallt if its tech is not very good. The pump may already be over.
These thaughts are based on the limited description you give only. Can you say exactly what "projects" you are talking about?
I am trying to decide between AEON and DASH. AEON does not even have a website yet and DASH has well funded marketing efforts in multiple languages. At first glance DASH seemed like the obvious choice.
However multiple BTC core developers (and highly respected cryptographers) have said positive things about CryptoNote. To my knowledge exactly 0 BTC core developers have said anything positive about DarkSend.