when you mention the word design for units...

[Sapphirus]

as the title says what do you think of the most when you mention design.  As for me?  the visuals (art)

[17thRecon]

I went with statistics, like “what was this Mech designed to do?”.

[Porshadoxus]

As I have no talent for art, and a love of Excel sheets, always stats.

[Charistoph]

It depends too much on the context of the conversation, and what else is said surrounding it.

Of course, for some it doesn't usually matter, like, "I like the Marauder's design", as opposed to something like, "I like the Shadow Hawk's design". 

Most people like the Marauder and the effectiveness of its loadout, so it doesn't really matter, however, the Shadow Hawk's technical designs (particularly in Introtech which is where people think of designs first where available), tend to be a poor performer, so usually references its aesthetics.

However, most conversations like this usually have other sentences involved in the conversation, so it's usually pretty easy to tell what a person is usually referring to and provide the context.

[Sapphirus]

3rd option added

[Maingunnery]

The art is quite essential for me, as some units are just too ugly for me to touch.

[Gray_Noton_4lfe]

I would say History should be an option but that probably falls in statistics   

[Stormy]

Yes   

[Jal Phoenix]

I think of that word as one I don't ever want to see in a TRO entry. I'll use it very sparingly. Because previous TROs are loaded with sentences like "The designers designed the design to outdesign other designs." And I'm not even joking.

[tassa_kay]

Like Charistoph said, it's about the context of its usage. Can we get a fourth option for that? Because that would seem to be the most logical answer to the question.

[Caesar Steiner for Archon]

It's interchangeable with "unit" or "mech/tank/fighter/etc." It's another way to make your sentences less repetitive.

[RifleMech]

For me art and function are important. Stats on a sheet are good but they're like a generic unpainted Lego minifigure. It has potential but without even a face there's nothing to make it unique. It's the art that turns a generic minifigure into something more. And it's function that determines the art and accessories. For me, its the same with a tank, fighter or Mech.