If you're open to discussion about this, I suggest that you lay out your reason(s) for wanting a freestanding tent. Unless you camp on wooden tent platforms or that sort of thing a lot, my limited experience in discussing this with folks is that they ultimately drop the "freestanding" requirement after they've worked through the issues and trade-offs.

That said, the rainbow isn't a bad choice, but even there --- I wonder how often folks put it up in freestanding mode vs. just staking it out??

Bottom line is that you have a lot more choices, and so can optimize for other things if you accept a non-freestanding tent.

And what do you mean by "waterproof"? I.e., do you mean something really specific in terms of mm of hydrostatic head, or do you just mean that you don't want a tent that leaks like a sieve, or ... ? For example, with silnylon you can get 'misting' which I don't find to be much of a problem; cuben is more waterproof and lighter, but also a more expensive fabric.

Another question: do you use trekking poles? I.e., would you have a pole or two along with you to act as a tent pole?