> am in the process of launching a new Open-Source project for Civil/Mechanical/Chemical engineers

I'm in this group (I'm a Materials/Chem eng). We have recently started using media wiki internally for all sorts of documentation related things it has taken off very quickly.

Over the years there has been other solutions pushed onto us like confluence and sharepoint those never really gained any traction.

Having plugins enabled (like math equation editor) is important - Engineering documentation involves Math equations. The wiki lets you use markup like this "\frac{dC}{dO} = \frac{10}{\alpha+\frac{\beta}{([C]-C_{min})^{DC}}}" but also has visual editor.