Oh man, I can't believe I forgot to mention Ash - just chucked her name in there.
Ash I would love if she was a little more mobile - if her Ult was either a tactical or just a lot lot quicker cooldown. Her Snare I find pretty useless, like maybe 5% of the time it does its job, maybe 15% of time it distracts someone, the rest of the time it doesn't really make a difference.
I play more aggressive with Ash. Crack shields and ult in or in a slugout do the quick dash to get a slight advantage. Or ult out of trouble.
Valk, I can do a similar thing to the Dash but it has to be used more defensively, due to time to switch back to weapon.
I'm zipping out of rooms and up levels with Valk, and so good to be able to easily bypass long journeys to get up platforms. And her missiles basically do what I would have hoped Ash's snare does. I find Ash slightly cooler, but love the mobility of Valk.
I left Valk til last as she was the most recent one for me who I'm currently sat using, waiting to get a decent skin for her. I only have common and epic.
When Valk first came out, I found her jetpacks a bit slow (were they slower?) Or maybe I was just playing her wrong.