Which one is better to take to r5?

STARKtech

LeNoirFaineant

Quake( im not perfect with her)

I'd practice hard with Quake for a week or two. Use her as much as you can. If you don't like playing her or can't get good, I'd go with Mags

Iron_Patriot_is_lit

Mags

You won’t regret it.

Edwin10

Mags

I recently completed Act 5 and I didn’t have a good counter for 5.4.6 Ultron boss, so I had to solo him with a 3 star Magneto. And it worked, Magneto can do so much awakened or unawakened, against metal or no metal opponents.

odishika123

Gaurdian

Yes

Malreck04

Quake( im not perfect with her)

Or mags

Kill_Grey

Gaurdian

I honestly wouldn't rankup mags just yet considering your progression level (I guess you're just a new cav or approaching it). A rank 4 mags can already do pretty much all the metal champs in act 6 as a rank 4. I would rankup Guardian first since he's the awakened one there (and since you're not confident in quaking yet). He will serve you well.

Real_Madrid_76_2

Gaurdian

Easy