Assuming you're talking about solo/small group --You can still do work on mag. I mainly play a magblade that can handle most stam classes, only runs into trouble against stam classes running around in a bunch of well fitted. I've also played a magsorc and magplar.
I also have a couple stam characters, and generally speaking I personally think they're much easier and stronger outside of coordinated group play.
Stamina is life in pvp, and you have a lot more of it to roll, block, and bash. Recovery is also much easier between weaving heavies and passives. Damage mitigation is better. You can wear heavy armor and not have to worry about sustain. You can stack weapon damage way higher and far easier than mag can without having to worry about sustain problems, allowing you to push crazy good healing while also having a ton of baseline mitigation. You can also throw on malacath and proc sets and literally let your armor play the game for you.
Mag classes can still do work, but stamina just has so many intrinsic advantages by comparison that it's easier and more forgiving.
Unfortunately the devs behavior of late appears to only be focused on making stronger proc sets, such that "low APM" players (their words) don't really have to learn how to play the game anymore and can simply let their gear play for them instead (what they call "narrowing the skill gap"). As these sets typically favor stamina, that also tilts the balance in their direction even more, so don't expect any adjustments anytime soon.
Xbox NA - JaeKwellen
AD PvP
Trying to main a magcro. This is awful.
The current state of the game is a complete disaster. There is not even a CLASS problem. the problem is that any class, it doesn't matter stamina, magicka or health can use the same sets, same items with the same effectiveness.
The PROC SET destroyed the game completely. stamina classes use a staff because the staff will hit the same it doesn't matter, the magicka will use a stamina set because the set will work even in a full mag class. healing is just insane to the point were you can forget about what is happening in the fight, you will heal yourself automatically, not even thinking about healing yourself.