The best replacement for antlr is javacc.

The best alternatives to antlr are rated as following:
★★★★★  javacc
★★★  bison
★★★  irony
★★★  xtext
★★  boost spirit
★  parboiled
★  pyparsing
★  yacc
★  gold parser
★  sablecc
★  ragel
★  llvm
★  coco r
★  lex yacc
★  flex bison

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

Other search terms related to antlr and their ratings are:
★★★★★ stringtemplate
You have in mind a companion for antlr and it is not yet here? Propose!



Google Trends

Scale is based on the average worldwide traffic of antlr in all years. Click on graph for more.
antlr
javacc
bison