it depends on what you want to use it for – got carpets ? both have proper revolving powered brush that will clean carpets.
Felix is more complex – X1 is traditional design.
Henry is simply not designed to clean carpets.
Got a felix pet and all i know is it’s powerful. Other half says that the attachments (floor polishing brush?)are awesome. But too good to suck up DIY rubble and crap so I have kept the old Panasonic for that.
I know it’s not on your list, but we have a K1 and it’s good. If the cupboard space is limited I think a K1 will take less space than an X1 or a Felix. Noting that RichPenny says the X1 was heavy, the weight of the K1 sits on the floor but you can use the long handle just like an upright.