Hmmm... very similar-looking games that play very differently. I don't think you can go wrong with either, honestly - they're both great in different ways. Doctor Who is a bit more complex, as the time expander has an extra stage to it beyond the JackBot visor, and has an extra flipper. It's the more modern, complex game for sure. JackBot has such a classic layout, though, and brutally fun gameplay. I actually really dig the music on it.
Gun to my head, at this point, I would say Jack*Bot... but if I get tired of it down the road, Doctor Who would be on the list of games I would consider trading it for.