Choose Gewerbeschule if it's CHF 250 cheaper per month, the commute to HB is 4 min shorter — more central and connected, there's a denser restaurant scene.
Choose Mühlebach if it's noticeably quieter (48 vs 56 dB), it scores higher on safety (8.5 vs 7/10), it has better green-space access (5 vs 3.5/10).