Choose Escher Wyss if it's CHF 150 cheaper per month, the commute to HB is 4 min shorter — more central and connected, there's a denser restaurant scene.
Choose Hirslanden if it's noticeably quieter (45 vs 54 dB), it scores higher on safety (9 vs 7.5/10), it has better green-space access (7.5 vs 4/10).