by choice

from WordNet (r) 3.0 (2006)

by choice
    adv 1: with intention; in an intentional manner; "he used that
           word intentionally"; "I did this by choice" [syn:
           {intentionally}, {deliberately}, {designedly}, {on
           purpose}, {purposely}, {advisedly}, {by choice}, {by
           design}] [ant: {accidentally}, {by chance},
           {circumstantially}, {unexpectedly}, {unintentionally}]

from Moby Thesaurus II by Grady Ward, 1.0

19 Moby Thesaurus words for "by choice":
      before, by election, by vote, electively, first, freely,
      gratuitously, in preference, independently, optionally, preferably,
      rather, rather than, sooner, sooner than, spontaneously,
      voluntarily, willfully, without coercion

[email protected]