Physique and build wise. Since they make great assassins, aswell as being potent in magic, it would make them agile and quick with some muscle, unlike the altmer who are tall and skinny-ish, and Wood Elves who are very agile however lack the amount of muscle dunmer do. (Correct me if I'm wrong.)

What do you think?

You forgot the Orsimer (Orcs). I think physically they're the strongest elves.

Edit: But during the Tribunal's heyday. Great House Indoril and Great House Redoran, had some of the finest warriors in all of Tamriel.

Ah yes, my bad. I was thinking more of the traditional elves, The Altmer, Bosmer and Dunmer. Orsimer, however, would be the strongest overall, I agree.

And yep, I thought this too. I think i've read somewhere that Dunmer are extremely strong/agile aswell, but the other elves seem a bit more nimble.

Personally I would go with Altmers as the strongest mer.

Orcs are great warriors but they are cursed and can only live 60 years.

Physique? Orsimer.

Well out of the three traditional mer races they are indeed the strongest.