What are the advantages and disadvantages of supporting a classical guitar? I know of three methods, each of which has some variation:

1. A footrest
2. [A stand or cushion that rests on the left leg and supports the guitar](https://music.stackexchange.com/a/5850/2156)
3. A strap

I recently bought a footrest, since I'm trying to add classical guitar techniques to my repertoire, but I found that it causes back pain by forcing my spine into an awkward position. I'm intrigued by some of the stands available, but they cost more money than I want to shell out without knowing if they're actually a good investment.

My preferred option is to use a strap connected at the top to the neck where it joins the body (I have a conventional strap, not one that connects to the sound hole). I've found that I can quite easily hold the guitar in a classical, neck-high position with a strap. Yet I haven't seen any good classical guitarists use a strap.

What are the pros and cons of choosing one method over another? And are there any other viable options I haven't considered?