The Antec P20C is a good chassis. It is well built & looks great. In terms of cost it clocks in at the exact same MSRP as the Antec DP503 (Editor's note: and it is even more expensive with the ongoing sales of both cases at the time of writing). That pricing doesn't feel as good as it could be as the P20C ships with plain black fans and no ARGB/Fan hub PCB - both of which should be considered price saving elements. That aspect is only offset by the higher quality front panel design, but even so - users may care more about tangible functionality.
The fact simply is, that besides the front design, both cases are exactly the same tooling. Antec has been quite successful - and rightfully so - by minimizing the different case tooling but offering alternative designs and fan/ARGB loadouts to gear individual models towards specific target audiences. This concept works quite well because of the solid, no-frills steel bodies of their line up. This also means that users will unsurprisingly compare the P20C and DP503 - both are marketed as E-ATX gaming cases.
With that in mind, the Antec P20C is a solid case. It offers uncompromising E-ATX compatibility, it's three fans are nice and quiet, you get a solid GPU support bracket to prop up your big 3-4 slot GPUs along with dual 360 mm radiator support, in combination with plenty of fan loadout flexibility. Maybe Antec could have added a fourth fan in the rear of the chassis - which would have resulted in better thermals while at the same time differentiating the case a bit more from the DP503 while taking a step towards leveling the bang for your buck equation at the same time.
We recommended the DP503 in our review and as such the P20C should receive and deserve the same level of recognition from a purely functional perspective. While you get more for your cash with the DP503, the crazy thing is, by today's standards, both cases should be considered well priced - just one better than the other. So if you like the P20C aesthetics and quiet fans - go for it. Otherwise grab the DP503 and turn on the light show.