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My home-made stands have a bit of tilt built in as I had a pair of stands for smaller speakers that also have a tilt and I liked that. I have a few half baked theories about why which I won't share for fear of embarrassing myself :)
I still manage to use the tops of the speakers for some objects but a plant pot might be a bit too much.
PMC are doing the trapezoid boxes at the moment. I don't like the look so much. I like the last one on your list but I don't know anything about the inside of the boxes and what implications that shape has.
They'd still be quite tall anyway. Having actually modelled it, even on the 200mm stands they need 2.5º. Going down to 100mm stands / plinths I need 5º. Trapezoid looks wack. Quite like square box just tilted back, but it means we can't put anything on top of them. Currently they're plant stands x speakers. Maybe tilted front & back with horizontal / parallel top and bottom.