Well, it would most definitely depend to the person you asked. If such a person was involved in enterprises in Asia or Brazil, it would give you a matching answer. The general view, if such existed naturally shifted through times, depending on the circumstances such as foreign relations and wars, to new economic developments

Since 1500 to 1550, and you could most likely extend it to 1580, it was most definitely their Indian Ocean operation. Portugal had a spice and trade monopoly, as well as some extent of slave and gold trade in Africa. To keep and extend this supremacy they poured money and soldiers into making their Indian Ocean Empire. They had an unmatched navy superiority, limited only by it's size. They (at least tried to) tax and control all the trade in the Indian Ocean, with establishing, by force or diplomacy, outposts in Goa, Hormuz, Aden, Malacca, Macao, etc. Goa, the Portuguese center in India, was considered to be as rich and beautiful, if not more, as Lisbon.

Brazil was at the time only a small outpost with lots of potential. First efforts into organizing Brazil happened in 1533 when 15 private captaincies were established (out of which only 2 prospered), and more concrete 1549 when Brazil was made into a Royal captaincy with a Governor-General subject directly to the throne. At the time Brazil was mostly exporting wood (for dye). First sugar plantations were started, but while prospering they were of limited importance.

Now, just to clarify, Portuguese monopoly on India was becoming less and less profitable. It was basically a bad economic practice. It suffered from corruption, vulnerability to sudden disasters (storms, pirates, changes in price of spices). It relied mostly on foreigners as investors and traders to distribute the goods through Europe, a position which put them in a disadvantage as well as cut their profits. And the financial military cost to keep it was becoming higher and higher, especially if we count the Portuguese attempts to take Morocco.

In 1580 Portuguese and Spain entered a personal union (which lasted upon 1640) that changed a lot of factors. Before this event Portuguese were large trade partners with English and Dutch, and suddenly they were involved in Spanish conflict with them and were cut off. They had to fund the Spanish land war in Netherlands, and be subject to more and more piracy from previous trade partners and ultimately all-out war. Ensuing economic crisis of the 17th century certainly didn't help

But new opportunities did open for them, as now they had access to Spanish Americas, as well as Philippines. Soon Spanish silver started flowing from South America, through Manila to Macao for trade with China. With more piracy around Cape and smaller market in Europe, and Portuguese control of most important port cities Portuguese trade turned more to inter-Asia trade then trade with Europe. This trade was mostly private trade, and the Portuguese crown had little involvement and profit in it. At the same time, Brazil turned into biggest exporter of sugar and tobacco, and slave trade with West Africa increased.

Since the 1620s he conflict with Dutch and English kicked up the pace with VOC and EIC (Dutch and English East Indies companies) starting to take territory in Asia, and WIC (Dutch West Indies company) fighting in America and Atlantic. VOC took in turn Jakarta (Batavia) and Spice islands, some islands of the cost of Africa, Malacca straits, blockeded Portuguese in Goa, and attempted to take Macao, All in all they generally slowly positioned itself as dominant power in South and East Asia.

However Brazil had equal if not worse problems. WIC took the northern half of Brazil from Portuguese since 1630. The guerilla resistance to the Dutch popped up in 1645 and slowly drove Dutch out in 1654, but at a cost of severely destroyed sugar industry infrastructure, with competition already in place in the Caribbean islands. However as in this battle on two fronts, the Portuguese seem to spent more energy and effort to fight in Asia and Africa, while Brazilians seem to have fought a lot on their own, which indicates they still valued Asia possessions more

Since the later half of the 17th century it seems that Brazil with its large area and mineral riches becomes more and more center of Portuguese interest and investment, with Asia losing almost all of the advantages. In 1693, gold deposits are found in Brazil, a gold rush ensues and since then you can say Brazil becomes the key interest of Portugal (or itself even, as it slowly becomes more powerful then Portugal proper itself)