Martin Lewis: Should I move my Help to Buy ISA into a Lifetime ISA?

Which is better, the Help to Buy ISA (H2B ISA) or the Lifetime ISA (LISA)? I'm asked this all the time. No wonder, as they both offer an unbeatable, no-brainer 25% bonus for first-time buyers saving in them – yet there are some big differences, so I've bashed out an answer...