I've had a Cyberpower system for almost 4 years, and at the office (an animation studio) we mainly use systems from them as workstations, and we've been running a number for years without ever having one catastrophically fail. This includes some systems that have been lugged around from home to office daily, lugged around the NYC subway system for demos, etc.
I'd actually say that CyberPower can be a pretty great deal for a pre-built system, but there are some caveats to that.
First, you need to actually buy and configure on their site. The systems from Best Buy, Amazon, etc. are much more expensive than the systems you can get from their site, can't be configured, and are likely to have some dodgy components. Now they do take a couple of weeks to build and ship (used to be more like a month,) so if you need a system now they might not be the best choice.
Second, you really want to catch good sales, and in particular sales where they're pushing something that you actually want. A lot of their sales are of the "free upgrade" kind. If you want the particular free upgrades they're offering that can be a great deal. If you don't care, it's not so great. And they often throw in some low-mid range peripherals for free. Whether or not you want/need them will affect how good the deal is.
Third, I mentioned that you have to configure the system on their site. You have to know what you want in order to do that. If you look at their stock configurations... well, I think they are a bit odd.
The PSU is one place where this is true- they tend to favor big cheap PSUs over good smaller ones. Or sometimes big good ones- one of the things they are pushing right now is a free upgrade to an EVGA SuperNOVA 1050 GS. . I'm not an expert on PSUs, but I feel safe in saying that this PSU is not likely to fry your system . But it's a lot of power supply for a pre-built $1200.00 gaming system that defaults to a single GTX 1060. Anyway, sometimes their default PSU choices are terrible, but they usually have some decent to good ones in the configurators.
There are other areas of weirdness as well, especially when it comes to pricing. I'm in the market for a new system, and have decided to build my own, but I was a bit on the fence about it for a while, and was looking at their current deals. One thing that really struck me is that going from the default 8 Gigs of Ram to 16 was at least $70.00. That is pretty steep for an 8 Gig stick of RAM- for the system I'm building I got 16 Gigs of perfectly fine RAM for about $51.00. But today their Daily Deal is a free upgrade to 16 Gigs.
And when I was looking at their configurator earlier this week the special was on an NVidia partner 1070 (an EVGA FTW maybe?) I already have a GPU I want to use, but removing that card only took $355.00 off the price. If I had wanted that card right now it would have been a better deal than it was without it. But that's generally the nature of configuring pre-built systems.
They also have a bias toward overclockable systems, which means not just slightly more expensive chips, but substantially more expensive motherboards. And toward liquid cooling. If you don't want to overclock and are happy with a stock cooler that again makes CyberPower a less good deal, I think (I haven't looked as hard at the pricing of their locked builds though, so I could be wrong about this, but that's my impression.)
I actually think that as long as you know what you want and configure your system properly CyberPower is a pretty good deal, and can be a great deal if you're willing to wait for the right sale, or just get lucky when you want to order. If it were straight-up a matter of money I would have ordered from them- at any reasonable price for my time it would be a lot cheaper than building. I just happen to want to build a PC, and also want to have total control over what goes into it this time.