Hate to be a nitpicker but:
Tango is almost gone as it was a failure
Snowflake is having awful trouble and may be shut down
Song is brand new - far too early to tell
Zip has stayed small and really can't be counted against the "might" of Air Canada
BmiBaby hasn't done badly but a few routes (eg; East Midlands to Brussels) have reverted back to full bmi service after the low-cost model was soundly rejected by business punters on the route
Freedomair hasn't done badly but certainly isn't a shining light.