Indeed, going through Delcourt's
dossier, it appears that most of their French-language comics are recent titles rather than the classics of the 1950s, 60s, and 70s which advnarayan mentions.
For those kind of comics, I would go to
izneo.com and read such series as Lucky Luke, XIII, Thorgal, Valerian and Laureline or the Bluecoats which are available in English.
As far as Delcourt's own French comics are concerned, none of their titles are familiar to me. Most of them strike me as thrillers or fantasies with dark backgrounds with little of the humour of Tintin and other similar titles. Probably more aimed at the adult market.
I've only read one series, "De Cape et De Crocs", and after three or four books I did not bother with the rest, even though there have been about 10 albums in the series. Still, some might enjoy it more than I did if Delcourt intend to release it in English.