I would like to add my personal view, which I see somehow between the two oppositions. I suggest a very important cause of the dispute is a different way of access to Epicurean philosophy.
The very common approach of reading the letter to Menoeceus is very clear in its essence. The letter argues, that we should prefer a life focusing on a peaceful state of lifing. It is argued, through making us independent from goods we do not need, wrong beliefs, fears etc. we achieve the best life imaginable and become generally independent from the difficulties of the world. The main problem is, that this approach doesn't refer to Epicureanism as a wider system of knowledge. Many thinkers only refer to the ethics as presented in letter to Menoeceus (additionally Principal Doctrines, Vatican Sayings) but do not apply Canonics and Physics, which they consider as a different point of interest.
For a person who studies all three main branches of Epicurean philosophy and even tries to combine and interconnect, it's something different. Understanding Epicureanism as a holistic system reveals that pleasure occurs in the beginning. It's a central part of Epicurus' epistemology. It is so important, because it occurs naturally. Searching for pleasure is not an abstract idea, it's an aim that is intrinsic to every lifing being.
In my opinion, Epicurus understood rightful, that pleasure is natural and central for every lifing being. We are not able to choose, we have to handle with our attraction to moments, which we perceive as more delightful than others.
In the Epicurean world, nature sets the standards. Epicurus reflects pleasure and comes to the conclusion, that it has to do with the conditions of our being. This is why he distinguishes between natural and not natural, necessary and not necessary. In other words: There is this basic impulse called pleasure and Epicurus examines this term in relation to the fundamentals of being alive.
In conclusion, we get an approach to the term pleasure which stretches from the Canonics to the Ethics by corresponding to the Physics.
In my personal opinion, Epicurus is neither looking for painlessness nor for pleasure as pleasure on its own. He tries to find out what a human is in itself. This is why he focuses on senses, feelings and anticipations. In relationship to a theory about the functioning of the world (physics) Epicurus derives his conclutions about how to conduct.
Consequently, satisfying all natural and necessery desires is the highest level of being. But being a sensitive being also means, that there are differencies in how this natural desires can be fulfilled and perceived. This is the flavour, which can tend to be not necessary (as Diogenes Laertios explains). This is why Epicurus advices only to fullfill natural but not necessery desires if they do not harm.
Finally, my personal view puts 'painlessness' in the centre, but it never occurs as that abstract idea as the word tends to appear. Ataraxia and aponia are related to the world made of atoms, which means that they will never exist perfect or erase the relationship with the world itself. We perceive painlessness only as a pleasureful state because it means, that we acquire everything what our natural fundamentals are looking for. This position is an important part of Epicurus' way to absolute freedom, but it remains only, if we remain near to the given fundaments, as set by nature.
As Lucretius tells to us at the beginning of book two of De Rerum Natura:
Lucretius. De Rerum Natura. William Ellery Leonard. E. P. Dutton. 1916.
