Compare the functions and locations each approach provides. One statement tree may combine climbing, scratching and resting in a visually coherent area, but it concentrates those resources in one part of the home.
Several smaller items can place a bed, scratcher or lookout where the cat already prefers to use them. They may also be easier to move individually, although their combined footprint and cleaning needs should be considered. Start with your cat's behaviour and the room layout, then compare suitable products rather than assuming one large purchase is always more efficient. In a multi-cat home, separate choices can be particularly useful, but the cats' relationships matter. The best arrangement is the one that gives practical access and comfortable options. A decorative focal point can be part of that arrangement without having to perform every function alone.
Map where each activity happens now. If scratching occurs beside the sofa and sleeping happens in a quiet bedroom, separate suitable pieces may serve those habits better than asking one tower in the hallway to replace both.
For product comparisons alongside this advice, see Linden wooden cat tower and Arbor Retreat. The details below explain their sizes and uses.
Further reading: cats.org.uk.
Linden wooden cat tower
Arbor Retreat
Floral Canopy