Seasonic SSR-650RM (G Series) vs. Corsair RM650? Which should I use in my build?

Sparktown

Honorable
Jan 28, 2015
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Got these two PSU's for $59.99 (after rebates - which I need to mail in a few days) for my first-time build. I couldn't decide which to use and they were on sale so I just got them both since I could return one later. Now I almost have all the parts together, so I need to decide.

My build:
CPU: Intel Core i5-6500 3.2GHz Quad-Core Processor
Motherboard: ASRock Z170 Pro4S ATX LGA1151 Motherboard
Memory: Crucial 8GB (2 x 4GB) DDR4-2133 Memory
Storage: Samsung 850 EVO-Series 250GB 2.5" Solid State Drive
Video Card: EVGA GeForce GTX 950 2GB FTW ACX 2.0 Video Card
Case: Corsair 100R ATX Mid Tower Case

I might also put an extra physical drive in there. Power estimates had me at around 380W. Wanted a good PSU, quiet and (at least somewhat) modular. No real plans to OC. Originally was going to get a 550W, but they were as (if not more) expensive than the 650W PSU's on sale.

Seasonic SSR-650RM
jonnyGuru.com: 9.8/10
Tom's Hardware PSU Ranking: 2nd Tier (I think?)
Don't know about noise.
Only semi-modular. The non-modular cables seem to be stuff you would have to have plugged in anyway, so really only annoying if I want to remove the PSU completely (maybe for cleaning). The non-modular cables do look a little thick though and I'm worried that my case might not have a lot of space for cable management.

Corsair RM650
jonnyGuru.com: 8.7/10
Tom's Hardware PSU ranking: 3rd Tier
Fully-modular!
Special silent operation features. I'd like my build to be quiet, but I'm not obsessed with making it as silent as possible.
All flat-cables.
JonnyGuru.com mentions something weird about "two dead 5V wires at the ATX connector". This has me a little worried because I don't fully understand what it means. An explanation would be appreciated.

I've been waffling back-and-forth. I feel the Seasonic is maybe the better PSU, but the Corsair has a lot of features I like. Then again, the weird dead wire thing on the Corsair still kinda worries me.

Anyway, I need to decide soon because of rebate deadlines. Which one should I keep for my build and why? Thanks.