Well I think they are both good arguments. However there will remain an issue for what you mean by 'God'. If you mean 'a Divine Intelligence' the argument is pretty solid. Einstein believed in a 'God' in the same kind of sense:
knowledge of the existence of something we cannot penetrate, of the manifestations of the profoundest reason and the most radiant beauty - it is this knowledge and this emotion that constitute the truly religious attitude; in this sense, and in this alone, I am a deeply religious man
I believe in Spinoza's God who reveals himself in the orderly harmony of what exists, not in a God who concerns himself with the fates and actions of human beings
Even the uber atheist Richard Dawkins endorses this kind of theism, or deism, in the God Delusion. The first chapter is called 'a very religious non-believer' and refers to statements of this kind by Einstein. (However in a biography of Einstein published subsequently by Walter Isaacson, it is made very clear that Einstein had an even greater disdain for atheists than he did for organised religion.)
(Actually Plantinga's argument is a proper rationalist-metaphysical argument rather similar to the First Cause argument. If every cause requires a cause, then there must be a first cause...and so on.)
Some questions about these proofs: What it the implication of believing in such a God? What difference does it make if it is true or not? How does it affect either the scientist or the ordinary person? Does it carry any sense of moral obligation or is it just conjecture? And if Swinburne's argument is correct, then will it yield enough results to empirically demonstrate the 'existence of God' to a non-believer? Could it form the basis for actual research, or is it more a question of interpretation of the what we already know. (The image that springs to mind is one of those cameras they set up in the forest to capture the elusive Greater Spotted Marmoset...:bigsmile:)
These are some of the thoughts that occur to me. However I am not much of an adversary because I favour theism over atheism. I will let some of the anti-theists have a go. No doubt they will cut them to shreds...