Here's my experience for what it;s worth - I have multiple cages in shelving/racks so have no "hieght" clearance.
The Skyline maxi side door is too small to enable effective cleaning/putting in igloos/inserting dustpan etc etc. I have two 120cm Skylines that are now redundant. If you have it on a rack and can;t easily access the top door, you need to pull it out for anything except putting in veggies/food.
Ferplast with it's whole side opening is good - but the plastic furniture puts me off and, again, if you have it on a shelving rack, it is more unwieldy to undo the side opening to put in food and veggies as you might not have any height clearance.
Liberta/Trixy - I have been looking at their 150cm cages recently and I get the impression there is only a ceiling door and not a side door (might be different for the 120cm - but check the width of any side door)
Personally I go with the Savic Nero 4plus every time as the side door is big enough to clean the cage and get the pigs out.
If you can access the top (ceiling) door in any of the cages mentioned then go for one of those. If you are only able to easily access from the side door because you don;t have the height clearance or the cages are stacked on top of each other, - then go for the Savic.
HTH
x