VMaNGOS its strength lies in its inclusion of work

3.3.5 emulators are not less suited in terms of quality when WOW TBC Classic Gold compared with 1.12.1 emulators. I don't know where you have this information from. Trinitycore has 34k commits as compared to 4,8k on vmangos. TrinityCore includes a number of features that are stable and performance, in addition, you are able to access a wealth of tools that aren't readily available for 1.12.1 emulators.

VMaNGOS its strength lies in its inclusion of work done while being used for Nostalrius or Light's Hope. There are a myriad of issues that can cause instabilities, attacks, and similar difficult-to-foresee issues that only becomes apparent on high numbers of servers. This is VMaNGOS the strength. Since its main purpose has been vanilla servers, it is scalable. It does one thing well and does it exceptionally well: vanilla. Darrowshire is a perfect example of this.Recently they also included an implementation of the Warden anti-cheat system.

Others have already said this but I'll try to frame it differently. If this is for entertainment, then go for it. If you're doing it for fun, then the program you use is simply something you choose. The WotLK client is better in my opinion, as it offers lots of new features you can tinker with, and the content is mostly similar, except for aspects like talents and abilities.

You're not wasting time trying to tackle this big project to buy TBC Classic Gold attract players from a vast base. There isn't much interest in custom servers and even were they to, their desire for new releases could result in them consuming your entire server in 3 months, when it took at least 1+ years for it to be completed.