depends on what your trading methodology is.
i get some alerts from RT's hottrend scanner. i get some alerts from ISLAND's 'most up' / 'most down' system (and then look at L2/intraday charts).
you probably want to determine what your system is - do you buy breakouts / sell breakdowns? sell tops / buy knives? buy pullbacks / sell pullbacks? before determining the type of scanner you'd need.
