7.72 got better dx support so if you don't want to mess with client gut, and you can get all 7.4 features in it without much of problems. Also I simply want to play on tiquanda like places on custom 7.4. Or dark cathedral. Also take balance back to 7.4 and if you got enough time and will, switch to old sprites(consider cutting borders out for easier mapping, and sprite replacement).
For a custom features tasks are quite fine. I would like to see tasks for skills also(sorry, hate long ass skilling) in limited form, so players could do task for skill 70-75 and it would give them around ~1,2 skill - if that was low rate. Also bits of non intrusive fluff and those strange tibia quests, which are to be found by exploration of game and learning of fluff(books, npcs dialogue but also item descriptions).
I'd love for items to be more custom rather than standard 7.4. Reuse rook items and rest of low level stuff or something.