I use MS but never used eS so can't compare, however it depends
on what you want a program to do, trial both, you might also look
at AmiBroker and join the forums of all of the above which will
provide additional info
You could choose to use both.... Metastock Pro for both real-time and daily charting + eSignal as the data source. I have been using that combo for several years.
I switched from Metastock to eSignal simply because of the poor/lagged quotes from Metastock. Sometimes quotes would just stop, or not load at all. eSignal has been perfect so far but I do miss some of Metastock's charting features.