If you think Blair will be both strong and effective, and you really want a weak presidency, then I find that a compelling reason to oppose him.

Blair wouldn't try to be strong and effective. He'd try to be strong, he'd be a disaster, and he'd totally discredit the institution. But just his mere appointment would be a PR mistake for the EU as a whole.

Just look at what he's done as Quartet Envoy to the Middle East.

The peak-to-trough part of the business cycle is an outlier. Carnot would have died laughing.

Now you're getting to a reasonable argument against Blair, finally.

Finally? I think in one for or another, all of my arguments were told by me and others in this thread.

Do you favor a strong President model or a weak one?

For that specific post or the EU as a whole?

• If the former, of course a weak one; I'd like to see the Council develop into some kind of a second chamber, in which the President is only a facilitator. Tony would want to turn this into something stronger (he would want it to become "strong and effective"). I am rather sceptical about his chances to succeed against the will of the national heads of states and governments, and probably the EP would put up some resistance, too; but even if he failed, he is unfit for the facilitator role.

• If the latter, I prefer the parliamentary model vs. the Presidential one; e.g. an executive getting its power from an elected parliament, rather than from the election of its leader. Why? (1) the Presidential model unifies the representative/identification role and executive power, thus reducing the role of political considerations in the choice too much; (2) a President in the Presidential model is elected first-past-the-post, while a parliament can represent a wider range of political views, and the government too if no opinion has absolute majority; (3) a President in the Presidential model is concentration of too much power in a single hand for my taste.
  
  IOW, I want a strong Parliament and Commission; which consequently means a strong President of the European Commission (and also strong Commissioners).

(Note terminology issue: in English-language countries, the Latin-origin term "President" in politics is rarely used for posts other than a combined head of the executive and the state. In many of not most other EU, however, corresponding to its original literal meaning -- c. 'chairman' --, it is used in combination for all kinds of posts -- f.e. "Minister President" in place of the British Prime Minister for head of executive, "Republican President" for a ceremonial figurehead head of state, etc..)

in Brussels

The Lisbon Treaty as is represents a compromise between the various players (e.g. the EU's main institutions). Behind that, winds blew in different directions in different quarters of Brussels.

What was the problem with the rotating presidency after all

Too messy. The holders of the office have to govern at home at the time, every six months there is a handover, and when there is a government crisis at home, the EU takes a second seat (see Czech Presidency earlier this year). I note that the rotating Presidency would stay on in the Council of the European Union (the day-to-day intergovernmental institution of the EU). I should also note that in discussions on ET, it transspired to us that the Lisbon treaty definitely solidifies the European Council as an institution of its own separate from the Council, which was seen negatively by most.

dominant constituency of institutional elites who want a strong, powerful presidency

Who would they be? Surely not the Commission and the bureaucracy under it; the Commission wants power for itself (even if Barroso is quite inefficient in seeking it). Surely not Parliament, which was against it and wants more influence for itself. As for the European Council, its members want power to themselves, but that quite obviously doesn't translate into wanting a strong power over their heads. Quite the opposite: they want someone representative to stand in the spotlight, who puts them in a better light -- more a figurehead than power position. (In Eurobarometer polls, the Council was persistently the leat popular EU institution with citizens; with the Parliament scoring highest.) For that reason, Tony would again be a bad choice; and I suspect that's why today the only voices for Tony for President come from Britain.

successful in the face of significant adversity

I am not aware of any real successes achieved by Tony.

_{*Lunatic*, n.
One whose delusions are out of fashion.}