In general, Acrobat is easier because it has lots of built-ins so you do not have to write javascript for everything. But Livecycle Designer has some very interesting options, such as forms that can shrink and grow, that Acrobat does not have. But lots of the extras on Livecycle have to be scripted.
So I have advised those who I have trained to use Acrobat to start. Once you have some experience with that, and if you need your form to do something that can only be done in Livecycle, then you can work on learning Livecycle.
But Livecycle Designer has some very interesting options, such as forms that can shrink and grow, that Acrobat does not have. But lots of the extras on Livecycle have to be scripted.
So I have advised those who I have trained to use Acrobat to start. Once you have some experience with that, and if you need your form to do something that can only be done in Livecycle, then you can work on learning Livecycle.