I won't tell you what to choose, but:
BPCW really benefits from high sigs, and can be worth the investment, but I'm personally not in a rush to get him. Medusa dupe is fun - especially when you're as bad at the game as I am - and makes her vaguely useful on defense.
Just my 2 cents.
I’d say get that Medusa dupe. She was my first R3, personally think she’s great.
she may be my first cosmic r4. Still debating.
People sleep apparently on how 3 m/m combos trigger a pretty lengthy true accuracy buff. M/l/m a few times to sp1 also covers mixmaster nodes. Only downside is it's not passive like Cull's. And yes, autoblock will cover an aggressive play style.
if you are active player / valiant, I would go for the new champ. Every month that goes by, the odds of pulling a champ from the basic get worse and worse. While at the same time, AGs are getting more accessible.
If you got about 80 sigs and are willing to rank 4 Black Panther, definitely go for him. I have a rank 4 unduped right now and I'm capping out at around 50 charges on average. Hits for about 62k bursts four times during sp2 with a couple second long bleed ticks for 2.4k x 3.
All I can tell you is I'm taking BPCW, and plan to use a skill AG on him and then take him to R4 when I get enough sigs to max him up.
BPCW is really good but he absolutely needs max sig
I think this is what I’m doing too. Can’t get a bullseye to save my life so need a decent skill attacker besides Yelena.
A new champ is better than a dupe in most cases. You might pull a Medusa dupe or get a cosmic AG down the line. Why don't you consider Purgatory? She's very good especially for questing, though not in the same league as Medusa and DPX.
As for BPCW, I feel there are a handul of skill champs better than him. I wouldn't necessarily invest an AG on him unless your skill class is severely lacking and your main focus for a new champ is BGs.