I've owned all 3 of the guns in question. The lcp obviously disappears in any pocket and won't weigh you down. It's also the least "capable " of the 3 (ec9, hellcat). Hardest to shoot, most jams, least powerful.
On paper not much difference between the hellcat and ec9, but I really miss my ec9 (well, and hellcat) lol.
I think the weight of 7 Vs 12 + 9mms can't be discounted. The ec9 has a different less boxy shape and carried very flat and organically front pocket.
With the 9 round back up mag I never felt under gunned.
Hellcat was also pocketable but seemed more noticeable and swung more when running etc.
In the class of lcp I'd prefer a sig p238. It's a good 380 "fightin " gun.
I'd like to get another hellcat or ec9. I was offered trade too good to pass up.
The hellcat is the most capable, good sights, fast return to target, most rounds, it also disassembled more easily (hate the Ruger ec9 lcp etc take down method. Cmon Ruger).
Most likely unless another ec9 drops in my lap for 150, I plan to get another hellcat and adapt.