As the article reports it was a Block 5 Merlin (aka the last Merlin upgrade). I don't believe qualification has started yet on Raptor but that would seem to be the logical next engine to qualify after the Block 5s.

That it exploded is oddly a good thing according to friends at JPL. They say that when ever there is a catastrophic failure like this it forces a deep review and root cause analysis which invariably adds additional understanding and depth to the design. Knowing what can cause an engine to blow up, and knowing you have designed around it, is a good thing.