I have used both, e-signal for data into TS2000i for several years then switching to TS online a couple of years ago when it became stable. Data was a real issue for me with e-signal. I wanted to maintain substantial history for back testing and had a flaky DSL feed that would drop off at least once a day so I spent a great deal of time filling in missing data. With TS all you have to do is enter the symbol an the historic data loads either from your storage if you have been using the symbol or from the TS server automatically if you have no or out of date data on your drive.
The other issue is cost. If you trade much at all, TS software and data are free. E-signal still has a monthly charge.