I've had success with a number of tactics on my Vita - Codfathers 442, andrichbrands The Man Utd Way, and The False Counter (mypassionforfootballmanager).
But definitely know what you mean about consistency, I often get a good run of results, then the AI susses me out and I have to constantly tweak/change tactic grinding out mixed results till the end of the season! Might just be a Classic mode thing because we don't have access to the finer details, not sure.
Most frustrating thing is seeing threads about amazing tactics but nobody shares the team and player instructions for the Vita players.