The important part about magitech is, as has been alluded to above, that it is device based and that it is recognisable as technology. Frequently, this means devices that are essentially magical versions of mundane modern technologies -- airships, but they fly due to a specific kind of magical reactor that generates lift when magical energy flows through it or whatever. So, you're kind of asking the wrong question here. Or putting the cart before the horse. If you're going to decide on a general aesthetic for a magitech society, you're going to need to answer at least the following couple of questions:
1. How does this technology work?
Crystals are popular -- they're associated with magic and mysticism in many different cultures and enchanted gems have been a staple of fantasy for-basically-ever. They're also really easy to visualise as a power source or a container for magical energy. As far as I'm concerned, there's nothing wrong with using something that other people have done before as long as it's not a carbon copy, but if you want to go with something else, you need to decide what you're going to use instead. When you find a device made by this culture, what is its power source? How does it work, what do the internals look like, generally? What do you need to make it work? What kind of affect can it have on living creatures or the envitonment if they're exposed to it? That's going to inform a lot about how the general aesthetic of the culture, which brings us to the second question:
2. What designs and materials make sense for your imaginary fantasy technology?
If you know roughly how your technology works and what the magic behind it fundamentally does, you can then decide what kind of materials and designs make at least intuitive sense. Do certain kinds of wood or metal conduct or insulate against magic better than others? What's going to be practical in terms of constant use or wear and tear? Does your culture produce machines that are sturdy and robust, in practical blocky shapes, or do they create intricate works of art that look more like something out of nature than a machine made by humans, or is it something else entirely? Our modern technology is primarily electrical or fossil fuel based -- it uses metal wires, plastic and easily refined metal, because those are the materials that are practical for the technology we use and the society we live in, and that's a similar mindset to what you want to have while you're designing your magical equivalents. It's your world and your magic system, so you can make shit look however you like, but the important thing is that it's internally consistent and can at least make sense in a reader's head. Always keep in mind that these devices are meant to be things that real people use in their everyday lives.
There's no real "best aesthetic" for magitech, there are only best aesthetics for specific settings and stories, and it's going to depend a lot on what you want to tell us about this culture and the sort of story you're going to tell. How the objects a society produces look can tell you a lot of things about them, and that's a world building tool you should stay cognoscente of. Personally, as I kind of implied above, I would avoid the knee-jerk urge toward novelty just for novelty's sake. Familiar looks and ideas with a new spin on them can work extremely well and be very memorable, and they became familiar in the first place because they resonate well with people. Don't avoid using shiny metal gears and crystals and glowy lines and shit just because the Elder Scrolls and a million other properties have done that already, if that really is the best fit for what you're doing -- just make sure your story still feels unique and memorable.
