I went through the same thing, and the key is three things: first, yeah, drain them really well and rinse them under cold water to get rid of that slimy broth from the can, because that's what leaves them flavorless. Second, while they're still a bit wet, toss them with a good dressing (olive oil, lemon, minced garlic, salt and pepper) so they absorb flavor instead of staying bland. And third, let them marinate in the dressing for a bit before you put the whole salad together, that way they blend in better. If your chickpeas kept coming out mushy, it was probably because you weren't rinsing that liquid from the can well enough and because you were dressing them together with everything else at the end.