I use the Wellbaby liquid, I just put it into his cup of milk. You can taste it slightly in the milk but it's sweet tasting so he drinks it quite happily
We also use the drops
I've got the mighty kids brand and either mix with yoghurt or Weetabix
My daughter likes the 'better you' spray ones. Taste a bit like mint chocolate. Only thing is, they don't have iron in them, but my daughter won't take any others, so I figure it is better than nothing!