To address your question ...one must read the question against the enviroment and threats involved in a specific nation. You might have noticed I used Nation and not county or state in this response. My take is informed with my experience, good intelligence apparatus relay alot on community intelligence. A sound Community intelligence infrastructure can be found amongst citizens of a nation ..i.e the Luo nation etc will be loyal to its nation cause the threats against the nation is personal.
You question seeks to know the powerful intelligence agencies in the world should be explained by the level of patrotism amongst a specific threat against a specified enemy. My take is Scandinevian intelligence communities and the isrealis have the best intelligence apparatus. You must understand that agenciencies with an infrastructure that enables information sharing amongst intelligence communities make the best intelligence agencies. Americans painfully knew the short comings that exsisted lntelligence communities and created a function of homeland security to address the gap of lack of intelligence sharing amongst american nations.. i.e Arab American nation, Black American Nation etc reservation against redneck states.
This then brings me to offer examples within our sub-saharan region. For instance Kenyan intelligence apparatus is rebuilding itself, ti is subject to actual excercise threats that are attacks the christian nation, in this regard religious patritism and fear of blowback is creating an enviroment where intelligence apparatus in kenya is becoming a global trend setter.. i.e lessons are learned on how to contain elements of domestic terrorism. This can be observed through the levels of interest western intelligence agencies show towards terrorist attacks in Kenya. Signet or signal intelligence has limits, however humint or human intelligence provides raw and actionable intelligence. This is a componet Kenya is breeding and its learning fast through the many terror attacks against its citizens (Christian nation). The level of patrotism amongst this population is growing fast ...
In conclusion, based on my assessments Scandinevian intelligence agencies are the best in the world ..i.e Norway, Sweden, Denmark Finland etc.