As far as I can tell, there were two proposals (not counting
variants) that seemed to carry some enthusiasm on this list:
Firebird: the legend continues
Firebird: because great minds think alike

Thinking about these two, and about SAP's slogan which I personally
like, I came up with the following:

Firebird: the choice of champions

(it sounds familiar to me: perhaps because it was already mentioned,
perhaps it is used for other products).

I think the slogan would fit well with the benefits that were
identified earlier:

Why is Firebird the choice of champions?
- Because it is capable
- Because it is reliable
- Becuase it is easy
- Because it is free

What is it like to work with the champions?
- Be part of a great, international, helpful community
- Work with stuff that is tried & tested in popular software stacks
- Experience the freedom, ownership & empowerment of open source

Who are those champions then?
- One million C/S developers use it to be successful in their projects
- SAS, the world's largest privately held software house, uses it in
high-end BI systems for its Fortune 500 customers
- FrontRange uses it for 15,000 mid-market customers, serving 1.3
million seats
- IBM Brazil is evaluating it on its zSeries mainframes.
- are you next?

In the languages that I know, it appears to translate well:
- die Wahl der Gewinner (Meister?)
- la choix de champs
- de keuze van kampioenen
How does it translate to Russian, Portugese, Spanish?