... first goes for Wakim's Game Improvements in combination with Economy Adjuster and Morrowind Advanced, while the latter just goes for Adventurers. Any thoughts on which one I should try out first?
Without giving quality comparison opinions (not that I shouldn't, I just don't have enough info to base that kind of opinion on), I can tell you that Adventurers touches a lot more actual objects. This will generally make it more conflict prone. I also seem to remember reading that it conflicts with MCA, if you ever want to try that out it may be worth noting. Personally I use a combination of tweaks including some parts of the modular W.G.I., Alaisagae's armor and weapon balance, etc. I think that you can personalize your game more by using multiple mods that tweak aspects of the game rather than whole-cloth overhaul mods.
I'd recommend Morrowind Advanced, as well as Piratelords Creatures X, and Piratelord's economy mod as well if you go for the modular tweaking approach. Of course make sure you're using Wrye Mash's leveled lists merger feature and TESTool for merging objects (carefully with an eye on load order and awareness of what's getting merged). Don't use TESTool for anything else really, there are better tools for everything else it does (No offense to Ghostwheel, who did a great job making it - it's just outdated nowadays. Rather it's a testament to it's quality that it's still the best tool for even one thing).