If PvP is your main goal I wouldn't weight in your friends Juggernaut in your choices too much tbh. Unlike PvE you won't hinder eachother by fulfilling the same role, not in queue times and not (much) in effectiveness. Note: The following is how I perceive the classes with some good and some bad points, aka it's an opinion. I likely missed a bunch, but I'm only human.
+ Quite difficult to shut down (meaning: not range dependant for survivability and has enough tools to stay on it's target and not prone to interrupts, stuns will be stuns though.)
+ Hybrid only: Quite high DPS whilst being bulky enough to Guard (mixes great with the Operative healer)
+ Good AoE in either DPS-spec (not quite Smash though
+ AoE Stun (short but doesn't break on damage)
- Prone to cleanse in Pyrotech
- Long build-up / predictable in Advanced Prototype
+ Rage: High Burst Damage that's an AoE aswell
+ Good defensive cooldowns (and a lot of them)
+ Teambuffs / AoE-stun for some teamplay moments (Best as Carnage)
+ Rage: 2 leaps for great movement, one works on cover. Carnage movement is decent.
- Annihilation: Cleanseable (for now)
- Carnage: Countered pretty damn hard by a good stun
- Rage: Being called a smashmoney and hitting great DPS-numbers without feeling you deserved them (this might just be me)
- Squishy early on, due to Cloak of Pain and Saber Ward I personally disagree with this, but it's been a dealbreaker for quite a lot of people.
+ Incredible Burst (likely highest from all rDPS)
+ Electronet is amazing
- Can be very tough to play vs the right foes
- More difficult to play the smaller the maps (read: Arena's)
+ Great 1 v 1 killing potential (if you're the one engaging the fight, you will most likely win it.)
+ Stealthcap that's almost fool-proof (Sleep Dart > Cap (enemy will use stunbreak or you cap) > Flashbang or Cloak > Sleep Dart > Cap.
- Prone to slows due to little mobility (what you do have is expensive)
- Tight on energy
- Prone to cleanse
- Needs stealth a lot more than any other class, in Arena's this is a huge problem
- People will be sad you're not healing.
I love playing Operative DPS, just for the fun of it, but I, in no way, think they're really a good class. They're squishy (for melee) and horribly easy to counter. They're possibly the best in a 1 v 1 situation of their liking, but that's it. Amazing healers though, but you want DPS, no?
I'd recommend posting your question on the PvP forums for more and better opinions and insights. 75% of the posts will most likely be trolls, but there will be helpful posts. If I simply wanted a plain amazing DPS and I had all 8 classes to pick from and the users would be equally skilled, I'd pick the Maurauder (Rage) or if I want a bit of a DPS mixed with support (Guard mainly) I'd pick the Powertech (or as full tank, but once again, you want to DPS, no?)