You don't really need to balance the markers in a team - usually teams have three ways of deciding what people will shoot:
1. Everyone buys what they fancy
2. Everyone buys the same to allow the team to pool spares + knowledge
3. Everyone uses the same because they're sponsored to do so
If you're pretty new to the tournament scene, just go for option 1 - buy markers that you like the feel of. It's probably a good thing having a mix in the team as you'll all get to see the relative pros and cons of each model and be able to make a more educated decision if/when upgrade time rolls around.
Every marker has its downsides - don't let anyone BS you that one particular make/model is gods gift to PB.
Taking the ones you've already got as examples:
Cockers
Pros - very popular, work well when properly setup, plenty of spares, upgrades and knowledge around, easy to 'bling'
Cons - can be daunting to tech as a first marker, if not setup right will run like a pig.
Angels
Pros - quick, tidy, plenty of people who know em + upgrades farily each to find.
Cons - some maintenance can need special tools, can be a blender if not setup correctly or you outshoot your loader.
Mags
Pros - small, indestructible, spares + upgrades easy to find, very easy to learn and maintain.
Cons - heavy for size (stainless steel), difficult to 'bling', unfashionable, can be harsh on brittle paint (without level 10).
I wouldn't get hung up on finding a particular brand (unless the person in question has tried a particular marker and really wants one), just keep an eye on the classifieds and look for the bargains when people are desperate to sell