Thaumcraft 4 (mc 1.7.10)

Found it amazing, the research puzzle minigame can be repetitive, however i enjoyed it. Items feels unique and really bring a magical aspect to minecraft. Some parts of the mod are slightly worse: most notably node searching, searching for one specific book (The crimson rites ) and getting aspects. The mod also has many addons.

Thaumcraft 6 (mc 1.12.2)

It is slightly worse than thaumcraft 4, it is basically a different mod as it got reworked a ton. The research is simple to comprehend but a bit too repetitive. The casting system got changed into a way nicer one, where you can design your own spells, which is great. The same book searching pain is also present here but there is a bigger issue: the mod is not finished (and won't really be) and doesn't have some end-game content that thaumcraft 4 had, it still however is great.