Arguments for God from a purely philosophical perspective

[Aegon]

Ignoring holy books and images of Jesus on toast, what are some of the purely philosophical arguments for God? 

I'm not well-versed in philosophy but it seems that a number of users here are. I was recently reading up on Aquinas and his arguments for God, specifically the "First Cause" argument. Aquinas is (basically) saying that life is a series of movements caused by other movers, correct? But there could not have been infinite number of movers. There must have been an unmoved mover that started it all. Sort of like a chain has to have that first starting link, otherwise the chain isn't a chain, as it's based on nothing and would fall. However it seems to me that Aquinas never really explains why God is used to fill that gap and why God is considered the unmoved mover. Is it because of the qualities God possesses? Perhaps He has the ability to transcend time because...well, He's God?

I'm interested in trying to understand more of Aquinas, but any other philosophical arguments in favor of God (and the ones against them too) would be welcomed. I find it all pretty interesting.