I strongly disagree with this ranking.
Their is no appropriate way to rank spy agencies due to high confidentiality. All of the well known ones have a history of accomplishments and failures.
In some cases, works of spy agencies are intentionally projected as what they are not in behind the curtains.
For example; When Bush Administration planned to invade Iraq, it asked CIA to build up a 'false but convincing case' to justify the invasion. CIA knew that Iraq had no weapons of mass distruction but interests of the country were given priority. And later on CIA was blamed for wrong Intel.
ISI is a great organization and I have no doubts on its professionalism. However, it is also overhyped a lot.
- The wave of suicide attacks in Pakistan
- TTP
- RAW backed insurgency in Balochistan
- Covert operations of CIA and Black Water agencies in Pakistan
Are all indication of a major flaw in our intelligence network. A sad truth.