As well as the wave option there are all the more traditional curtain styles from your basic pencil pleat formed with tape and a variety of other tape formed headings to many different hand formed headings as well as Eyelet headings. As a general rule tape formed headings are a more cost effective option although this can sometimes be outweighed by the fact that you tend to need a bit more fullness in pencil pleat curtains to make them hang well whereas Eyelet curtains can be more economical in terms of fabric usage so sometimes it depends on the price of your fabric which will the best option for you.
Bay Windows can be tricky but the wave track is great for Bay windows but if you'd like a more traditional style of curtain you can get tracked poles which are a fantastic solution. Evans Evaglide pole system is a very cost effective and fantastic looking option for Bay Windows and because it works like a track whilst looking like a pole you have no dipping corners or catching joins.
Pole or Track
Poles tend to be more expensive but are a bit more decorative. The pole on the right is part of Byron and Byron's Rustica range which is a stunning range of chunky rustic poles. It's a great way of making a feature of a small window. Eyelets need to be dressed on a pole but are not suitable for bay windows.
More traditional headings such as pinch pleat seen here tend to look better on a pole but for very wide windows a tracked pole will be better because the pole can be supported by brackets between the end and centre points.