I have this exact M3 Pro config shown in the photo. I use it to run some reasonably heavy simulations (optimization algorithms) in Matlab, with a fairly large number of variables and demanding computations (matrix inversions, SVD, etc.). It is super fast - depending on the simulation under consideration, it takes anything from 1 up to 10 minutes (we are talking here about thousands of simulation runs/iterations, large matrices, alternating optimization algorithms etc.).
The base max will be faster (say anywhere between 25%-35% of a boost in multi-core performance), but for your workload, I don't know if you will see any meaningful difference which justifies the additional money that you would have to spend.
I mean, in my case, 25% faster means that 10 minutes of simulation runs becomes 7.5 minutes. Ok, so what? In order to enjoy meaningful performance gains, I should have a simulation that now requires, say, 100 minutes (i.e., 1h40mins). Then, I would save 25 mins of run time. But at the speed of M3 Pro 12C/36GB and my workload, it is highly unlikely to find a use case where I need more than 15, mayyyybe 20 mins of simulation runs; therefore we are talking about saving 5 minutes at best.
Your use case/workload might be different, I don't know, but from my limited experience with small projects, I don't expect compile times of 100 minutes or so; thus, I don't expect meaningful performance gains from base m3 max over full-spec m3 pro.
On the other hand, I have to note the following: 1) You might have higher storage needs than me (512GB for me seems fine for now). To this end, you might go for the 1TB config of M3 Pro 12C/36GB, which is another $200. Then, jumping to the next level (base M3 Max) becomes more intriguing, because you are almost there.... I know! This marketing practice is disgusting and brilliant at the same time. (Keep in mind, though, that opting for the 512GB config and adding some external SSD storage might be a workaround to the above "problem".) 2) There is always the notion of "future proofing". You probably want to keep your new machine as many years as possible, and M3 Max 14C CPU is for sure better on this front. (36GB of memory might become a bottleneck faster than the CPU itself in the - not so near - future, I believe).
I forgot to mention that regarding single-core performance (everyday tasks like web browsing, office applications, video streaming etc.), both machines have the same performance since they utilize M3 cores and they are really fast (in fact, some of the faster single-core CPU performances across both PC and Mac worlds).
No matter what you will choose, they are seriously Pro machines and you will enjoy them. They will certainly fit the bill for your use case (with base M3 Max might being a little bit overkill, but not much). At the end, if you like the base M3 Max and you have the money, don't overthink it, just go for it. The fact that you want it is, in many cases, good enough reason!