I hate trimless tanks - like others said, they suck to clean because the magnet splashes water over the rim all the time.
Black trim is still quite common. At least you don't get the splahes, and I like that you don't see the water line. However, I'm not a big fan of black on tanks, be it trim or the stand, or th light fixture as I think it looks dated.
I strongly dislike the typical non-polished 4-piece eurobraced tanks as I think it looks messy and unfinished. I also don't like that it gets in it the way when you're working in the tank.
On my own tank I chose one-piece eurobracing all polished up with black silicone, and it is pretty slick. It does still get in the way when I'm working in my tank which annoys me, but I still enjoy the look of it. I got a friend with a 3D printer to print me out some custom corners for a flush-mount screen. It has a nice finished look to it. I ran the return line down through the eurobracing along the back.
Here's a quick cell phone pic:
