You can't really judge by the starting servers, because there are a lot of starting bugs that got grandfathered. But that's off topic....
I tried playing trader and researcher so far. It looks like with the new fixes, scientist would have an upper hand on expansion. So at start scientists will be better than any other class hands down.

However, as you advance The need for RO groves and traders become effective. As a scientist I tried to use trading to obtain RO and it seams to be a good alternative.

As far as playing a Warlord, I haven't tried one yet, but I'd say it looks like the most challenging class to play. Because they have nothing going for them to gain the boost of RO and those super capital ships are expensive! Maybe a month into the game is when warlord will gain power over other classes (if they are not killed off first).

So to recap:
Scientists - fast at expansion in early game.
Trader - average at start, but picks up speed when demand of RO goes up
Warlord - average at start, but picks up power mid/end game where 1000 ship limit becomes an issue (due to availability of super capital ships).