For me, aesthetics are just as important as actual effectiveness. I mainly play sentinels, but I've gotten ones with elec and storm blast to 50, so I think I have good experience with both sets. Elec is by far more straight forward and direct to use. That being said, if you want to project the feeling of actually conjuring a storm, storm blast is the way to go. It also has the advantage of dealing a variety of different forms of damage - energy, cold, & smashing. It also has 2 location-based powers, if you prefer those over more insta-cast ones.
With all that said, level 35 is a sweet spot, progression-wise, so if you are already enjoying the character, stick with them. If you're not sure, install the Homecoming Beat/Test server, where you can insta-level a character to 50, (or whatever level you want), so try out storm blast there and compare it to your experience on live.