no, arena, bc it's like all of the provinces, that would be the best option
Very true, but the game is so old and in such an old style that it would never look exceptionally better if redone in HD, without entirely rebuilding the game from scratch.
And if you're doing that just for all the provinces, you might as well stick with TES:Online or a single-player version, even though it's not the entire world at the moment, and is slightly iffy on Lore (mainly just to accomodate MMO gameplay though).
HD remaking Arena might be cool for Arena fans, but I daresay that it's of that traditionally old style of video game that it probably wouldn't be well recieved by all modern younger TES fans.