The Death Adder has long been the "good" product Razer makes. Their Keyboards, while nothing special, are "solid" IMO as well, but their other stuff, headsets, etc - IMO and general opinions online not as much. I ran an Adder with my Razer KB system and the mouse is excellent. I prefer Steel Series, still the same old "Microsoft" shape that I'm used to after so many years of using their mice, it's excellent for the $ as well, Sensei or other models, simple, work well, etcetc. Just pick a decent make you like the feel of, depending on your grip (claw/palm/etc) and go from there. Logitech's new mice are very good, well built, they have great vids out online showing their construction and design methods, but there are at least a dozen I would use and feel fine with - I just like the Steel Series due to the familiar shape, and easy/simple software, plus they are accurate for their rates.
Keyboard wise decide if you want mechanical switches or not. They are usually better and more tactile than regular switches, and there are various types (red black blue brown) which have different levels of "click" and pressure. Brown are good all round and are quiet, blue are loud, good for some types of games/gamers, and so on. Once you pick your switch, THEN pick your keyboard type. Filco and Ducky make very solid, heavy, simple RGB mechanicals which you may like if you like the simple look yet having features, otherwise Roccat, Corsair, Logi, etc all have good mech gaming kb as well.
One good option is find an IBM model M older mechanical keyboard, these have an older yet never beaten buckling spring key system which is still the best bar none, IMO. I find them from free, to 25$, and some for over 100$ in new condition still. You'll need an adapter most like, but that's simple/cheap. NO pretty lights, but they work well, and Unicomp remakes them in black if you're picky, but their switches just aren't quite as good I find still.
Monitor - I'd pick a 144hz monitor for sure in your shoes. You can get a 24" one in the mid 200$ range. 144hz will make more of a difference in how your games look and play than ANY other feature IMO, including free/Gsync, 1440p, TN/TPS, or size. It'll give you the ability to go above 60 observed FPS in your games (up to the 144/165/etc hz of the monitor) and give you a much more fluid picture than a 60 max one will. Every single person I've shown or recommenced to go to a faster than 60hz (100, usually 144 or 165hz) monitor has NOT gone back. Ask around here, you'll get similar responses. Jumping to 144hz is the cheapest, yet as said single BEST option you can add to a "gaming" LCD. All the other stuff helps and can be great too, gsync, freesync, higher rez 1440p/4k, and IPS panels, but none of these things do what 144hz over 60hz does just all on its own to such a great degree IMO.
There are a number of Asus, BenQ, and others which make a pretty inexpensive gaming 144hz 24" LCD -
VG248QE from Asus is available everywhere, I've had 3 of them over the years, still in the mid 200$ but worth it. Others can be found on sale from time to time too, I've seen 24" BenQ 144hz for 150$ before.
