For panel layouts, script writing, and lettering/balloons/captions, there is nothing better than Comic Life 3. Period.
Now, CL3 does no art. You will wind up doing that in another programme, but for everything else you need for putting together a comic, or publishing it, Comic Life is the best programme I have tried. It has drag and drop lettering directly from your script, over 100 pre-set page layouts, and you can customise to your heart's content, or build the page from scratch. It takes all of your fonts, and makes them immediatly available for you, and lets you drag, drop, and autocrop your panels. It's easy to use, and I have not seen any better way of layout or lettering.
Eagle
(And no, they are not paying me!)