Hi, OP!
One week ago, I was exactly in your shoes. When I was younger, around 13-14, I was hooked, and got as fast as ~18 averages. Haven't cubed since 2008-ish. I left a cube at my office desk, and a few people asked me to demonstrate. After a little bit of practice, I could get to frequent sub-20s again, and just like that I'm hooked again. I think in the last week, I dropped maybe around ~$70 on cubes already...
Let me give you a summary of how I felt coming back. Firstly, I'm assuming you're interested in hardware. When I was at my prime, Cube4You was leading with some of their new Type A-D, and DIY's were just starting to fall off. These days, all of the main manufacturers are Chinese and seem to have comparable competitive "flagship" cubes, and even some of the slightly cheaper ones compete. From what I've seen in the community, here's kind of a "Tier List" I've made, and maybe some popular cubers that use them. I think a lot of what's in Tier S/A are debatable and are personal preference, so I weighted them by popularity/release date.
-------------------Tier List-------------------
3X3
*Newer cube, so tier placement may be up for debate
Tier S - Gans 356 (Feliks Zemdegs), Aolong V2 (very popular community choice)
Tier A - Thunderclap*, Congs Meiying*, Hualong, Weilong, Yuxin 3X3 (Collin Burns), Tanglong (Saw Collin and Kennan Lejeune testing solves on it recently)
Tier B - Gans 357, Aolong V1, Fangshi Guangying, Dayan Zhanchi (one of the most popular but older cubes), Congs Yueying, YJ Yulong
Bigger cubes are a little bit more clearcut with less choices:
4X4 - Moyu Aosu, Yuxin 4X4, Cyclone Boys, Shengshou
5X5 - Yuxin, Huachuang are the clear leaders, and other popular choices are Cyclone Boys, Shengshou, Aochuang
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It's amazing to see all the rising talents in the competitive scene. When I started, big names were Andrew Kang, Yu Nakajima, Harris Chan, Chris Hardwick, Jason Baum, and slightly before them with Leyan Lo, Toby Mao, Dan Harris, Macky, and so many others. The fact that <7 averages are frequent just blows my mind. CFOP still seems to be the leading competitive solving method, although a few cubers have gotten quite low with ZZ/Roux. However, these days, the best cubers supplement CFOP with X-Cross, ZBLL, Winter Variation, COLL, VLS, ELL, and other various algs and sets to cut down times and cases. Going through example solves of people like Feliks, Collin Burns, Kennan Lejeune, they all seem to incorporate various algs from these techniques/sets.
Lastly, I want to say, holy crap Feliks is inhuman. I can't believe I'm witnessing someone who is near-genius level in terms of comprehending how to approach speedcubing as a science. This guy is like the Michael Phelps of cubing, he can go into any major competition with the chance of breaking a WR in any major category. The guy has what I think is the best combination of pure mechanics (turn speed, finger tricks) and solving efficiency (color neutrality, x-cross, LL recognition, etc.). I've learned a lot about what is seperates him and others in the last week from his channel and his blog, so maybe that's something you want to check out.
Anyway, it's great to have you back! I'm super excited to be involved in this scene again, it's absolutely fascinating how far the speedsolving has come over the years. Cheers!