WebKit is based on the KHTML rendering engine. And honestly, I really don't want another engine that is at least that worse/primitive as WebKit.
Amaya is rather a web development software than a browser. But for its WYSIWYG display it has of course some basic browser/rendering engine capabilities. Therefore I don't need Amaya. If you are in search of a good and free WYSIWYG web authoring software then try
Kompozer.
I'd rather like to have Opera's Presto engine as a fourth option in Lunascape. But you know, it's not open source and therefore you had to pay for the licence when using that engine elsewhere. And I'm quite sure noone would spend some money just to have Presto in Lunascape as long as you can download and use Opera for free, isn't it?
I would be more than lucky if a future Lunascape update will contain a more current WebKit engine which hopefully has many bugs solved and does also support Java.