It depends on what type of music you like more.
The Dream Sequencer is a great, mellow and atmospheric album and Flight of the Migrator is its counterpart - heavy, dynamic, etc. with guests such as Dickinson, Allen, Deris...
Into the Electric Castle has some really great stuff on it, but imo it has a lot of filler in it as well and most of the time it is between those great parts and brings the songs down a notch.