The best replacement for pen tool is live trace.

The best alternatives to pen tool are rated as following:
★★★★★  live trace
★  illustrator pen tool
  photoshop pen tool

Your alternative for pen tool is not listed? Suggest!
Speaking about pen tool, one probably shouldn't forget about vector mask.

Other search terms related to pen tool and their ratings are:
★★★★★ vector mask
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pen tool
live trace
illustrator pen tool