Each has strengths and weaknesses. For me, I've always found ESig lacking. They nickle and dime you on stuff like number of symbols, the charts look clunky, they don't give you enough intraday data and what's with all those pricing plans. They do have data from every conceivable market, and users say it is reliable and timely.
QCharts has brilliant charts, a great interface, lots of intraday data and some cool indicators and features that they basically don't say anything about. It's all in there but you have to dig it out. They have really awful tech support, their website is frustrating and impenetrable and they have had issues with stalled or lagging data in fast markets. I believe their delivery problems have improved, but you probably will be using IB to trade anyway and can doublecheck against their price feed.