Should I select a lighter/brighter shade of Emax veneers due to translucency?

Thank you for the excellent question!eMax porcelain veneers are not that translucent, and it really depends on how much your teeth get prepped for the final porcelain. There is a minimal amount of tooth reduction that needs to happen in order for the eMax porcelain to maintain its strength and not fracture. That amount of reduction is usually enough to mask out the color from your natural teeth.Other materials such as minimal/ no prep feldspathic porcelain veneers are very translucent and allow for the natural tooth color to shine thorough. These are the most nurtural looking veneers.So to answer your question. Whatever shade you pick should be the final shade of the porcelain. 

Hi:Color is based on personal preference and subjective.  It’s best to whiten your teeth and discuss the color of the crowns one more time with your dentist.  Prior to cementing the crown take a look at the color to make sure you are happy with them.Best,Dr. Maddahi

Having veneers placed is a huge decision for you towards a confident smile - my clients tell me they feel a spring in their step they never knew existed. So I totally understand you're doing your research and you seem to be the kind of person interested in details.
If that's the case, if I were in your shoes I would research the dentist providing the treatment. Choose a cosmetically-focused dentist who uses magnification, demonstrate their previous results, can be bothered to explain that they're going to preserve as much natural healthy tooth as possible, simulate the outcome using 3D models or computer simulations beforehand, and then give you provisional veneers to 'test drive' for at least a few days.
I assure you - if they do all those things, they will choose you the right ceramic material, prescribe the right thickness so they don't look translucent (e.max is the less translucent of the most common types, by the way!), and they'll also be working with the best technicians in the country/ beyond. The artistic skill in their eyes/hands is MUCH more important than the shade of e.max, I promise you.

Hope that helps. Best wishes for an excellent result
Zak