Adobe InDesign is the dominant player in the Desktop Publishing world. It is used for many books, and also for magazine and pamphlets, and even things like greeting-cards and invitations.
It is almost $1000, and having used it, if I were in the business of professionally producing books, (esp, with complex layouts), I would say it would be worth every penny. How ever, at the moment I'm only doing it as a hobby.
It's lower-end cousin is MS-Publisher, which can be replaced with Scribus. (Feel free to answer with a argument that suggests Scribus can replace InDesign)
conTeXt, a cousin of LaTeX seems like it might be a alternative, but the learning curve seems steep (the few times I've tried).
LaTeX itself might be a good alternative, but it seem that it forces you into the mould of what ever document class you are using (eg memoir, koma-book), and that to define a document-class of your own, you need far more than beginner knowledge.
- Must be Desktop Publishing Software, not word processing, not website design.
- Must support kerning
- Must support advance Open type features: Ligatures, Swash/Titling/Contextual alternatives.
- Should have support for structured document data import/templating (Thus allowing separation of presentation from content. (This would be a huge plus for me).
- Should have Mail Merge (which is similar to the structured data import, but simpler)
- Ideally would have better support for OpenType style sets, than InDesign has, but I can live with no support for style sets, as InDesigns support is only just usable.
Cost/Licence: Must be free, Ideally would be Open Source
OS: Any, with slight preference towards Linux > Windows > Mac > OS/2 ...