1. Stainless steel microneedles
Advantages:
- Extremely sharp
- Extremely hygienic
- Easy to clean and to sterilize
- Not as durable as titanium
- Prone to wear and tear
2. Titanium alloy microneedles
Advantages:
- Extremely durable and robust
- Highly resistant to wear and tear
- Highly resistant to bending
- More aesthetically pleasing, particularly the gold-plated varieties.
- Unhygienic
- Requires more cleaning and sterilizing
- Needles not as sharp as stainless steel
I have used both metals and I see and feel not significant difference between the two kinds of metal. This might be because I replace my devices regularly and never use them beyond 6 usages. For me this is important because it's my skin and I want to treat it the best I can.