I've finally chosen electrician B based on the following factors:
  1) He took the time to explain things clearly, offered options, and discussed the pros and cons of each.
  2) He advises against replacing things unnecessarily, often saying, "Can change if you want, but the price will be higher."
  3) He doesn't cut corners or suggest shortcuts (e.g. looping wire from an existing socket).
  4) He's listed on the Suruhanjaya Tenaga website.
  5) He works with his dad, and both his father and his father's company (which has been around over 25years) are also listed on the Suruhanjaya Tenaga website.
  6) He's neither the cheapest nor the most expensive.
  7) His office is just near my house

I'll post an update once he's done with the work—hopefully next week. Here's hoping for the best!