What is the most optimal relationship between a manager and his employees: Bossy or Friendly?

Good question sir. Both friendly and bossy nature are needed to manage employees. Too much freedom (friendliness) can make employees to take things for granted, so a combination of friendly and bossy nature needed. It also varies with experience level of employees you are managing..

Respect

To keep the required distance and respect to each other is always helpful than to become a close friendly relation. And moreover a friendly relationship existed before being introduced to the company need not be changed for no reason at all. Always Continue a pleasant relationship which is helpful for self development with respect and value each other.

I would intuitively say "friendly". Nobody likes to be bossed around, even when they have to accept it. And I somehow think that bossy people would withhold from being bossy if "friendliness" would yield the same result. But the fact of the matter is that the type of relationship is not always based on degree of effectiveness, but on something totally different.

It usually answer such questions with a standard reference to "CULTURE" and the importance of the cultural dimension in determining the best mode of relationship between a manager and subordinates. This is of more importance in multi-cultural work environments & in the management of workforce in multinationals, where there is no specific dominant culture to be named.

In the end, it always depends on what's deemed more "natural" or "normal" according to how high or how low the society culture scores on the so-called "strength of social hierarchy". A business culture is often a reflection of a society's culture, too. Meaning, how do people (managers & subordinates) perceive status and power in their society?

1. As close enough to be friendly with, allowing friendliness to be the norm?
2. Or as far away to be afraid of, enforcing "bossiness" to be the norm?

Example: in some cultures, it would be strange from a mighty CEO to be very friendly and on the same level with a janitor, laughing and joking, cause they simply expect him and/or demand from him to be unfriendly and arrogant. Why? Cause there should be a clear "power-distance" between them based on their cultural social hierarchy, otherwise his authority may risk being undermined or doubted!

For more in-depth commentary: Hofstede's Cultural Dimensions Theory (specifically: the power-distance dimension) 

The answer to this question depends on many factors related to the work environment, to the load of work, to the age of the boss and that of his employees...It is true that there should be no borders and obstacles between the manager and his employees but it is better to have a professional relationship between employees and their boss. this applies at least should be applied in work premises. When the boss is young he can understand more the mentality and thinking of his employees while when getting older he tries to show a more bossy character.

The optimal relationship between a manager and his employees is the relation that built based on the trust and respect and shared objectives. As a manager you must to find a way to establish this relation and I believe that,to be a leader "not a boss or friend" is the key to build this relation.    

Friendly in a Bossy way an unseperatable method or be a boss is a friendly way

I am a person who believe in maintaining the balance. I prefer to have a bit of everything the maintain the balance. Too much of anything would spoil things. So when it is required to be friendly to maintain the pleasant atmosphere in the workplace, we should do it. And to see that it doesn't go beyond limits a healthy amount of command we need to have.

Very tricky question, A manager is as good as his team, at times he has to impose his wishes whereas at times he need to understand the employees view point. 

Friendly touch pays more than the bossing style.

Relationship should be: Friendly Boss.

Being bossy is surely not an appropriate approach to improve efficiency from your employees. However, it is imperative to be assertive to achieve targets. The best approach would be to build a good relationship with your employees by understanding their requirements (personal, financial, skill development - trainings, growth) to enhance their motivation levels. This would yield better results. Neither be bossy nor friendly, instead be a leader.