The best replacement for leeks is green onions.

The best alternatives to leeks are rated as following:
★★★★★  green onions
★★★★★  onions
★★★★  scallions
★★★  shallots
★  chives
★  fennel
★  onion
★  green onion
★  ramps
★  spring onions
  leeks
  scallion
  leaks
  bok choy

Your alternative for leeks is not listed? Suggest!
Speaking about leeks, one probably shouldn't forget about pancetta.

Other search terms related to leeks and their ratings are:
★★★★★ pancetta
★★★★ romesco sauce
★★ roast dinner
You have in mind a companion for leeks and it is not yet here? Propose!



Google Trends

Scale is based on the average worldwide traffic of leeks in all years. Click on graph for more.
leeks
green onions
onions