The best replacement for threaded is threadless headset.

The best alternatives to threaded are rated as following:
★★★★★  threadless headset
★★  flanged
★★  threadless stem
★  crowned barrel
★  non threaded barrel
★  waxed
★  pinned barrel
★  waxed eyebrows
★  slip bulkheads
★  threadless
★  soldered
★  cantilever
★  socket weld
★  non threaded
★  externally threaded
★  smooth presta
★  sweat
  multi threaded
  smooth presta valve
  multithreaded
  treaded
  pinned sks
  prefork
  english threaded
  threadless headsets

Your alternative for threaded is not listed? Suggest!
Speaking about threaded, one probably shouldn't forget about threadless headsets.

Other search terms related to threaded and their ratings are:
★★★★★ threadless headsets
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Google Trends

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threaded
threadless headset
flanged