Timo Juhani Lindfors timo.lindfors@iki.fi
(I also think that the name pdfreaders.org is bit misleading since it does not list the most popular pdf reader in the world but I guess renaming it to free-pdfreaders.org is already too late...)
I think you mean most common, not most popular... I've heard many of its users swearing about it! They were quite happy to discover alternatives... although it seems that some still use Acrobat to fill out non-standard forms sometimes.
Regards,