What's your price range? Assuming you're looking to spend less than a Transformer, for example, your best bet is probably a rooted Nook color. I've personally used an Augen GenTouch78 (resistive-touch) and Viewsonic g-Tablet, and neither were ideal for comic book viewing. Resistive-touch is a real pain in the rear, can't pinch-zoom, makes panning difficult, etc. So I wouldn't recommend anything that has resistive touch (all of the $100 or less Chinese knock-off tablets). The g-tab has capacitive touch which is much nicer, but its screen is horrible. It's halfway decent in landscape mode, but in portrait mode it's extremely painful on the eyes. So I can't recommend that, either. You really do want an IPS panel.
Personally, I'm now using an HP Touchpad (yes, I know, blasphemy! And I'm not even planning on putting Android on it). If I didn't have that, I'd either look at rooting a Nook Color, or if I needed a larger screen an Acer Iconia or Asus Transformer.