Both have their strengths it really comes down to which play style suits you best (fun wise also). While you will read many posts around how stamina everything is dominating PvP right now you can be assured over future DLC releases that this will change and people will be ranting about how magica builds are dominating.
For me I actually have one of each for PvP and can honestly say based on my limited PvP skills they both work quite well. I like stamina for the weapon animations, lots of stamina for dodging etc. The magica is great for the ranged abilities, extra healing etc.
PS Of course there are also plenty of posts on how OP radient destruction is for damage.
Edited by dennissomb16_ESO on August 19, 2016 1:01PM