As per my WBJEE rank(GMR 131) l may not get CSE( 1st choice) but may get ECE or IT in Jadavpur University. Which of these two branches might be more attractive for higher studies if l am not allotted with CSE?

First of all congratulations for your result. The cutoffs change every year as it depends on various factors. And Jadavpur University is among the top government Engineering colleges of India. So the cutoffs are enough higher compared to other colleges. Now your General Merit Rank is 131. Going by last few years' cutoffs, you can expect Electronics and Communications and Information Technology both in Jadavpur University, if not in first round, but by the third round of counselling you get your desired branch. Last year, after third round of counselling, CSE was filled within 107 rank. So it might be difficult to get CSE in JU. You can also use our WBJEE college Predictor tool to know where you have good chances http://www.careers360.com/wbjee-college-predictor
Now ECE and IT Both are good in Jadavpur University. Being one of the best colleges, the professors are extremely talented and experienced. But if we see the placement Statistics, then placement for IT is better compared to ECE. Around 45 to 50 software and IT based companies come for recruitment. The placement for ECE is pretty good. Both the branches have higher studies option. Through GATE you can get into best colleges. Now it depends on your interest and passion which one to choose.