First post here, so please be gentle. 
This is a very hypothetical question, but you’ll see what I’m getting at.
Given the choice of a P20 with stock (black, $1) mains cables to connect to amplifiers or a P15 with AC12 cables, which would you choose, and why?
I would choose the P15. Because I don’t like the handles on the P20. Others will offer better reasons one way or the other.
Welcome to the forum. You’re going to love it.
A one dollar cable will sound like a one dollar cable no matter where you use it in your system.
Choose a power plant by the capacity of your system (or your bank account).
While I, too, dislike the handles, P20. A components’s performance is more important to me than looks. And a “naked” P20 will outperform a P15 with better cables; components are more important than wires.
Of course everyone has their opinions. I love the handles and think the P20 is one of the best looking pieces of audio gear out there. Others seem to agree. To date it’s rapidly become our most sought after and best selling Power Plant yet. We cannot make them fast enough.
Go for the P20. You’ll appreciate why the handles are there! My BHK 300’s are a pain to maneuver without handles. As for cables, there are many options both new and used out there at great prices. Get what you can afford then revise down the road.
As others have chimed in I would choose the P20 connected with a coat hanger for a cable over the others. They’re all good, but honestly, the P20 is head and shoulders better than anything we’ve ever heard or built.
FWIW, this would be to power Meridian DSP8000SE loudspeakers.
Huh?? In that case, maybe one P20 for each Meridian.
Well this made me me laugh out loud and now everyone in the diner has looked at me like I’m a mad man. 
Thanks Paul; that answers my question completely.
Buy the P20 and use the stock cable. Upgrade the receptacle to ensure a good firm connection.