Just to confirm, you know for a fact that she wants a distinctive style engagement ring and doesn't want input as to what style it is?
A note about stone cuts:
The shape has an enormous effect on light reflection, pear shape (or tear drop as you referred to it) is always a terrible shape for light reflection. Because of its angles it has a "bowtie" shape of darkness in the middle where light sinks right through the stone instead of reflecting back.
The optic benefit of moissanite over diamond is that it reflects light more brilliantly than diamond, so picking a shape that's guaranteed to lose light kind of wastes that benefit.
The reason most people get a round cut is because it loses the least light, being round and symmetrical allows all facets to be optimally angled for light. Princess (square) is almost as good, but something like a traditional emerald cut will just let light sink through, making it look more like glass.
As for design, that's so going to depend on personal taste, so I really can't comment on the options you've posted. Any one of those could either be loved or hated depending on the recipient.
I personally have a pear shape stone in a very unique and ornate setting, but I knew I would be losing light in the center stone when I chose that shape. I didn't care because it's surrounded by small brilliant cut round stones, which compensate for the lost light.
My previous rings were round, princess, and oval, and the difference is very noticeable. Yes, I've had a lot of diamonds.
If she doesn't care about any of this, then don't worry about it too much. However, if you want the most glitter, which is kind of the point of these expensive little rocks, then perhaps stick with the predictably brilliant cuts, especially when you can't see them in person and she's not the one picking it.
