I have dipped a toe in the water that is Izneo who offer French BD's to read on Android tablets and I pads.http://www.izneo.com/
The link above is to the English language versions which are available. Not too many yet but more appearing all the time. I'm in the middle of reading a French one, the first vol. of Agence Hardy and it is a good read. Cost 5.99 Euros. to buy but books are available to rent for 10 days for 1.99 Euros. I did have a problem with the app and how to read off-line but I have sort of figured it out, although the off-line reading controls are a bit limited. Certainly worth a go and I'd be curious to have reactions from any of you who try it.
(Blake and Mortimer, in original and new adventures are most entertaining; I've read a couple of issues of Lady S and enjoyed them; Scorpion is simply excellent and, in fact, there is something for everyone and nary a superhero in sight.)