For the record I implemented parser generator in C# just because I couldn't find any working properly or similar to YACC (see: http://sourceforge.net/projects/naivelangtools/).
However after some experience with ANTLR I decided to go with LALR instead of LL. I know that theoretically LL is easier to implement (generator or parser) but I simply cannot live with stack of expressions just to express priorities of operators (like * goes before + in "2+5*3"). In LL you say that mult_expr is embedded inside add_expr which does not seem natural for me.
