First of all, if you don't understand some of the things I say in this comment please check out Keyboard University, it is a great place written by people who have much more experience than me and are far smarter and more helpful.
https://www.keyboard.university/The Tofu65 is a tray-mounted board (meaning it screws directly into the case) which creates hotspots in tension and a feel that has zero flex or give and will feel like your standard across-the-shelf gaming keyboard. My personal recommendation would be the QK65, a Gasket mounted 65% keyboard kit made out of full aluminum with a SS weight. It is around 150$ for the barebones kit (Case, Plate, PCB, Stabs, All the foam you would ever need, A thick silicone dampener, and weight) as opposed to the Tofu65 which is slightly more expensive. This isn't to say the Tofu65 is necessarily "bad" but maybe not what you are looking for
Gasket mount explanation: instead of screwed in its PCB is sandwiched in between two pieces of foam or silicone which squish down on the case to give a more forgiving typing experience with no tension hotspots, despite this with a lot of gasket mounted keyboards you are likely to not notice it and it's a more minor thing but is a far better feeling than a tray mount. To describe the feeling of tray mount it's like taping cylinders to your fingers and typing on concrete whereas a gasket mount is more like typing on a stiff pillow.
QK65 Pros: Full Aluminum Case, SS weight in many different options, Gasket mounted, Multiple Gasket materials to customize the feel, Reputable designer, Sold on different vendors for different locations to minimize shipping cost, lower cost than Tofu65, Not much hollowness even without any foam or silicone, Many foam options to customize the sound, very deep sound with recommended config, comes with exceptional OwlStab LiquidMetal:tm: stabilizers that don't require Holee Mod to reduce rattle,
QK65 Cons: Not much room to flex with foam/silicone added, runs every few months (next is mid-may i think), You need phone number verification to join their Discord server if that's even a con,
My recommendation for a first build would be a QK65 (with your preferred color), with Epsilon switches if you like linears, Boba U4T's if you like tactiles, Krytox XHT-BDZ or Dielectric Grease for Stabilizer wires, Krytox 205g0 for the switches if you are going to lube them which exponentially improves feel and sound, and whatever keycaps you prefer but for the price total I will be using some 40$ GMK Dark Olivia clones from Aliexpress. This will total out at 290 dollars with room to replace the current 40$ keycaps with some more fancy GMK or whatever you want, keep in mind this is just an estimate although so expect the price to vary.
For a bit better explanation about the QK65 if you are convinced I would recommend
https://www.youtube.com/watch?v=MHj_dq4YQccand Jaeyou Park also has a sound test for every foam/silicone config on his channel if you aren't sure on which config to use. Keep in mind there are many different things that affect sound tests.
QK65 has the options for an FR4 plate, PC plate, POM plate, and Alu plate,
Alu=high pitched and stiff, FR4=slightly less stiff than alu and super deep, PC=super flexible and slightly less deep compared to FR4, and POM=slightly less flexible than PC and relatively "poppy"
You also have options for a Hotswap and Solderable PCB, Hotswap means you don't have to solder the pins of your switches into the PCB and is slightly more expensive, and solderable means you have to solder your pins into the PCB.
SA Profile keycaps are the more deep option due to the increased room inside the keycap which can then be filled with more plastic to make it even more
thick and usually the thicker the keycap the better, cherry profile keycaps have a more middle-ground sound and IMO are more comfortable so when you aren't going for a super deep board cherry profile or DCS profile would be the way to go, i would say SA can get uncomfortable to type on especially on the higher rows so take that into account. IMO SA profile keycaps sound a bit harsh to my ears and "square" if that makes sense? There are also alternatives to SA such as MT3 which have a similar sound but can fix certain things with SA.
If the QK65 isn't flexible enough for you there are two options: Get a half-plate by cutting the plate around the alpha keys and soldering those switches that no longer have a plate, or replace the gasket "socks" with some real gaskets such as the D65 gaskets and see if that is better.
Make sure to lube the switches if you want the feel to be super smooth and for it to sound just like you want, here is a video showcasing how:
https://www.youtube.com/watch?v=44Wv4OGdmu4The stabilizers are what make or break a board so make sure to do a good job on them, the stabilizers that are included with the board are fantastic thanks to their tight wire tolerance and liquid metal stabs although if they are made bent you may have to order a new wire for 3-6 bucks off Divinikey. Alexotos has a great video on how:
https://www.youtube.com/watch?v=vxHb6CJc9V8 DO NOT TUNE THE WIRES OF THE STABS INCLUDED THEY HAVE LIQUID METAL WIRES INSTEAD OF STANDARD WIRES AND MAY EASILY SNAPFoam/silicone can also affect how a keyboard may sound, the most common example is case foam where you put foam or silicone under the PCB to reduce hollow space in the case and can reduce hollowness/ping and could possibly make the board slightly quieter depending on the keyboard itself. A simplified explanation of the most basic foam/silicone mods is: PE foam is a thin sheet of (usually white) packaging foam known as PE foam in between the PCB and Plate under the switches which can create a sound that resembles marbles and is usually loved by those new to the hobby. Plate foam is a foam that also goes in between the PCB and Plate but this time instead of being under the switches it is around the switches where the plate cannot isolate, this can act to bring out the lower pitches in your keyboard, help fight your keyboard sounding muted and "plasticy", and make the keyboard slightly quieter. Silicone does the same thing as case foam although gives a different effect to the sound, it does a better job at making the board quieter than case foam does but also makes the board sound more muted and plasticy and is a great option for silent builds or other situations but in your current build likely isn't what you would want.
I would also recommend making sure when reassembling the stabilizers to make sure the stem of the stabilizer has a side with two holes facing toward the open area in the housing and to insert the gold wire of the stabilizer into the lower hole.
While the QK65 might not be as "thocky" as you are looking for it is definitely on par with the Tofu and with SA keycaps, some deep sounding switches, foam, and time and effort it can be on par or even better than the Tofu65 sound test Brendan B made. To prove this here is a sound test from NearLucid
https://www.youtube.com/watch?v=Ds3oTfut0QQ and even with this there is still room for improvement for the maximum deepest sound like an FR4/PC plate or high profile keycaps
I'm sorry if you actually read through all of this and please feel free to ask any questions if you need anything!
