I will say this, I do like the concept of 'objectives', that is why I choose to play Battleground's at the moment. Battlegrounds have abit more of a strategic element, (like a chess-game with counter plays and such) that I don't think arenas have, this brings a little bit more of a balance. even though arenas show great mechanical/combat skills, at the end of the day its usually the OP classes/p2p advantages that make you win.
I'm an f2p rogue keep this in mind, I'm sure if I was for example a p2p druid I would enjoy arenas more.
Now yes OP classes/p2p advantages still have their advantages in regular Battlegrounds, but I have more options, I can avoid one sided fights, go for objectives, steal flags, steal bases, ninja cap, etc, so I don't feel completely useless.
When it comes to pure Mono-E-Mono PvP, with no objectives, I would experience alot more one sided arenas as opposed to one sided battlegrounds, arenas do seem fun though, I'm not against them, I'm sure if I was p2p I would play them.
If I was a p2p, that had all the BiS PvP advantages then of course I would play more arenas but unfortunately as an f2p its very unrewarding, with no achievements/name titles/ratings to give either, and its a very short match compared to a battleground.
To me battlegrounds seems so fun, with so much people involved, its an event, especially AV, I guess that's why I find it more appealing.
Also personally I'm looking to get justice points, and the 'Justicar' , 'Of the Alliance' name titles as a side goal for my PvP efforts.
Arenas do have potential though, I can see myself playing them in the future if things change.