Ladies and gentlemen, I am Yuzral and some of you may have heard of me when I pop up and make videos on STO from time to time. Aside the Foundry Frolics series and occasional videos from Tribble, I recently did a video on the Advanced Dyson Science Destroyers, which can be found here:
Please watch and leave comments if you have any (the more constructive feedback I get, the better!) but the brief summary, if you don't have the 16 minutes or so to watch:
Federation: Competing with the Vesta, which is more flexible and almost as well armed. Probably losing by a narrow edge as a consequence, but more durable and a solid competitor.
Klingons: Best all around science ship currently available.
Romulans: Probably the best science ship they currently have, but the Scimitar and Dhelan both have decent science suites and a LOT more firepower. Consider those instead if science isn't an overriding priority - and the Fleet Ha'Nom if it is.