The Twittersphere gushed and guessed after Bloomberg reported the cloud software giant has hired financial advisers to evaluate takeover offers. No names were named, nor do we know just how many suitors may be courting. But it would take some pretty deep pockets to pull off what would easily be the biggest ever takeover of a software company. If (and that’s a big IF) Salesforce decides to sell at all.

Yes, Salesforce is a pretty attractive, albeit expensive target. It recently topped $5 billion in annual revenue, faster than any other software company. Next goal: $10 billion. Here’s the financial scenario for any acquirer: Salesforce’s stock ended Wednesday up 11.6% to almost $75 per share—giving the company a market capitalization of about $47.1 billion. Trading volume was five times heavier than the daily average. Does it really need to tie itself up with a massive merger that could stall its momentum?

If a deal comes to pass, which union would be most fruitful for buyer and seller?

The feel-good favorite is Microsoft, which has become a much closer ally since Satya Nadella took over as CEO in February 2014. Within months, the two once-fierce enemies forged a broad strategic relationship.

What broke the ice? Salesforce CEO Marc Benioff last year poached one of Nadella’s top employees, with his permission.

“Satya was talking about what he is trying to achieve with the company and how he wants to be more collaborative,” Benioff told Fortune’s Adam Lashinsky in January. “I decided to test him. I told him I wanted to hire one of his technologists as head of our infrastructure. What would be in it for Microsoft is the foundation of a partnership that would give us more kinds of ideas of things that we can do together. And he said okay.”

Clearly, the two companies already have a good working relationship. What’s more, both have literally thousands of business partners. Both Salesforce and Microsoft have created fiercely loyal ecosystems of entrepreneurs who have built big businesses by building business applications on their platforms. Plus Microsoft also has the cash required to pull this off: around $95.4 billion in cash and short-term investments, as of its latest financial report.

The second-most logical suspect is Oracle. There’s plenty of history, including the fact that Benioff used to work for Oracle co-founder Larry Ellison, and the latter was an original investor in Salesforce’s startup phase.

Sure, they haven’t always been all that nice to each other on the public stage. But that’s mostly for show and Oracle’s cloud religion has become rather profound over the past 12 months. Plus, their account lists probably are highly complementary. There’s also the matter of Oracle’s succession plan. While co-CEOs Mark Hurd and Safra Catz are certainly logical candidates, neither of them has Benioff’s leadership charisma.

Does Oracle have the money? It had $13.7 billion at the end of February but could probably raise at least $30 billion more pretty quickly based on its balance sheet.

Three other wildcard but worthy candidates: Hewlett-Packard, which could really use a strategic boost for its enterprise strategy heading into its corporate split; IBM, which has managed plenty of software acquisitions in the past, although management has its hands pretty full trying to convince the world that it is the world’s most important cloud computing and data analytics company; and SAP, another legacy software player that could use more momentum behind its cloud services vision.

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