I already gave the conditions in which you should use 1×3 or 1×1:
1×1 or 1×3, which one gives the best utilisation ? Well, it’s about the same !!
30 freq in 1×1, with load = 12% –> 3.6 TRX / cell max
3 x 10 freq in 1×3, with load = 30%
–> 3.3 TRX / cell max
The main question is about your radio design:
large overlaps, heterogeneous terrain, hills, overshooting, reflections, high antennas –> prefer 1×3
sharp cell coverages, good downtilt, homogeneous terrain, regular inter-site distance, regular antenna azimuths –> you can use 1×1.
The better is 1×1, because it shares ALL frequencies at once. So any improvement on the radio design gives great results immediately, in terms of QoS and capacity. Also, it is easier to manage after a while.