Which gift has more benefit for the giver? What are the dangers? There is the case where a person gives toward a monk, having a joyful perception of the good Sangha, while he gives.

There is the case where a person assumes a certain monk assuming being a Noble One and gives with such a joy.

There is a person who is not able to trace either a monk nor the Sangha and gives an householder, willing to think "more worthy is he".

What would give the most benefits? What are the problems for an ordinary person, and a most secure way? What are the dangers of overestimating ones capacities of judgment? What it a person thinks that his ideals are those of a Noble One "I know", yet total wrong?

(Note: this is not given for trade, exchange, stacks or binding entertainment here, but as a tiny door to escape the wheel corrent and since a long caught in)
The most beneficial giving (dana [Pali], act of generosity) is that which is done without the thought (without the conceptual constructs) of giver, giving and reciever. 

The prbolem for an ordinary person, like us, is that we start evaluating the worth of the giving, worth of the person to whom it is being given and the worth of what is being given. (Certainly these are important things to think and decide, certainly there is merit in them as well; but the most meritorious, the highest dana  goes beyond these conceptual constructs). WHen we think of worthiness, we get caught up (attached, we cling, we grasp) with these thoughts and therefore loose more merit that would have been gained if we were beyond the concepts of giver, giving, receiver and other related notions as worth, etc. 

One danger of overestimating one's capabilities is that we would make wrong decisions (since we have not judged our own capability correctly). 

'Noble one' are categories that help in positing the progress of people on the path of Nirvana. One can only make correct judgements about people who are behind oneself in the path (ref. Arya Candrakirti's 'The Entry into the Middle way'). We cannot judge people who are at advanced stages as compared to us. All we can judge is that they are ahead- for such progress on the path shows in one's actions, speech and thoughts.