I use dvorak, even though the TB I have shows qwerty. But then, I've used dvorak for years with qwerty layouts so nothing new there.
I think colemak is supposed to be easier to learn (fewer key changes than dvorak). I've read opinions on the advantages of each, but my impression is that few people would ever notice. But I think both are better than qwerty. Even if there is some disagreement over which is faster, both dvorak and colemak involve less effort than qwerty since you spend more time on home keys so that is good enough.
As for what layout to actually display, for your own use, it probably doesn't matter much if you are touch typing because you do most by feel rather than looking. And I'd say it is harder to see the keys on a TB because the vertical distance is so much less that a higher percentage of keys will be blocked by your fingers - unless you actually are moving your fingers out of the way while you look for some character you aren't used to.
For friends who may want to try your keyboard, usually they are probably using qwerty and would benefit from seeing the proper layout. Since I've ordered two, one qwerty and one dvorak, I'll keep the dvorak at home since that's mostly where I use it. But I'll take the qwerty on trips (though it will still be set up as dvorak), so any friends or relatives I visit can use it as qwerty (I always try to keep one slot set up for qwerty just for this reason).
There is one other thing some may want to keep in mind, since we can customize darn near everything. While I use a dvorak layout, there may be some things people choose to change since they can. IOW, you can create your own modified layout based on one of the major choices - probably usually some symbols/punctuation. If so, whatever layout you order from WT may not be 100% accurate. But that's your choice. I guess WT could set up something where you could order a customized version, but I don't think that would be worthwhile. After all, you may do some customization only to later decide you want to customize it a bit differently.