Assuming the project is a library or a tool that people will need to somehow embed in their program I wouldn't go with GPL. It has some restrictions that are for various reasons hard to accept for a large amount of clients. People try arguing that "you could do this or that to accommodate" but the fact is that many for-profit corporations, even those working with open projects, will have a no-GPL policy. Also with the current trend for web services and what not GPL can be worked around, hence the AGPL.

I'd probably go with LGPL and commercial plugins that enhance the functionality. But this depends on the product having some features that could be mainly useful for companies but not really for individuals.