The biggest reason over Pathogen is automatic installation of your dependent plugins. Biggest reasons over Vundle is parallel downloading, dynamic plugin loading, and static plugins. (all of the reasons for me, YMMV)
I've found even that I can install vim-plug with only a few lines of vimscript so that I don't even need to store a .vim directory in my dotfiles repository. Everything can just be installed and run the first time I start vim on a machine, and I can easly :PlugUpdate to get updates to any of my installed plugins.
FWIW, this is also quite possible with Vundle. I keep my plugin management in a separate file which also contains the Vundle bootstrap logic for new systems. This stanza sets up Vundle if it isn't already installed...:
I've found even that I can install vim-plug with only a few lines of vimscript so that I don't even need to store a .vim directory in my dotfiles repository. Everything can just be installed and run the first time I start vim on a machine, and I can easly :PlugUpdate to get updates to any of my installed plugins.