Similac Total Comfort v Enfamil Gentlease

We are on total comfort and doing way better as far as general fussiness and gas is concerned but it's so hard to get the powder to dissolve...I have to shake it so much that no matter how long it sits, there are still a ton of bubbles in the bottle.  I'm considering switching to Gentlease...it comes in ready to feed which is like to have as an option...any thoughts?  Have you used one or either?