which one should i choose?

I like Logitech products better, good quality and durable than other brands
Razor blackwidow is also good but a friend of mine had an issue with double clicks around most of it keys after 1 year or so. I would recommend to check corsair as well, they got good quality keyboards also ! I have k70 and is great

I actually did own the G513, I picked it up from Best Buy during a sale they had at $50, which is a steal considering its MSRP. For the price, I paid I'd say it's great. There's a ton of RGB settings if you're into that, and the lighting looks really fluid. I gave it to my younger cousin since he made a new PC earlier this year, and needed some peripherals, but during the time I had it, I had no problems with it. I loved the switches(GX Blue) since I normally type on tactile switches, I liked the satisfying feedback the switches offered. I tried the Razer Blackwidow Elite once, they seemed good too, didn't have much time to type on them, but I've heard Razer switches are decent. Honestly, it all comes down to preference. If you have the chance to try them out, do so because you might prefer different things than I do. RGB software on both keyboards seems on par with one another, G HUB, and Chroma are both meh, but they work fine. I personally use a custom-built board with Holy Pandas right now, and obviously, I think it's significantly better than Logitech, and Razer's offerings, but hey a mechanical keyboard of any type is still miles better than any membrane board.