In another debate with Bill Craig, atheist Christopher Hitchens gave this objection: "Who designed the Designer? Don’t you run the risk… of asking 'Well, where does that come from? And where does that come from?' and running into an infinite regress?" But this is an elementary misunderstanding in philosophy of science. Why? Because every successful scientific explanation faces the exact same problem. It’s called the “why regress” because no matter what explanation is given of something, you can always still ask “Why?”

IMO, it is perfectly reasonable to object with: "Who designed the Designer?".

The logic being objected to is: it takes a big complex thing to create another big complex thing. Observing that Darwinian evolution makes big complex things from scratch is the counter-example. The intuition that a complex thing (humans) requires another complex thing to create it (god) is wrong - and it does tend to lead towards an escalator of ever-more-complex creators.

Simplicity creating complexity needs to happen somewhere, to avoid an infinite regress - and if such a principle has to be invoked somewhere, then before the very first god is conjoured seems like a good place.

Checking with the "common sense atheism" link quite a few people are saying similar things in the comments.