Amazon will inevitably create a reading-focussed colour Kindle at some point, but a larger screen would be very expensive, while dropping the weight means reducing the battery life. (Open up an iPad and most of the internals are a giant battery.)
As it currently stands, I quite like the iPad (I have the original one) for comics and magazines, especially when travelling. I caught up with a couple of mags while on holiday and read all of Starlord as CBR files, because I didn't have the luggage weight to take my originals with me. I think it's a pretty good platform, not least because you have Comic Zeal (CBRs), a couple of dedicated comics apps, and then a ton of PDF readers—even iBooks is fine for PDF mags and comics.
As for alternatives, there really aren't any yet. Other tablets exist, but they're mostly a similar price to the iPad and inferior in various ways.