Considering the small difference in price between the FM10 and the FM3a and the big difference in quality and durability, I would definitely go for the FM3a.

As a lover of manual/mechanical cameras, I was seriously considering the FM3a as a replacement for my three aging F2 bodies (I have been using one since 1971). However, I changed my mind when I discovered that film bodies have dropped so low in price that I could purchase a used F4 body in excellent condition for a little over $300 compared to the price of $500 for a new FM3a,

I donít know if the automatic/electronic F4 will last me 30 plus years like my manual/mechanical F2 but I am willing to bet that the FM3a will last you that long.