Still here. :-) 

Is there a curated collection of lvlworld maps? Like, a bundle of the best, for each category/theme? 

Oglerau - Sort of:

- https://lvlworld.com/search/lvl : hand picked maps placed in a number of map packs over the years.
- https://lvlworld.com/topmaps/ : For all map types. Use the "+" button in the bottom right to filter to different game types.
- https://lvlworld.com/filter : Another way to filter maps.
- https://lvlworld.com/searchadvance : Select the attributes you want. More like a search with a filter.
- https://lvlworld.com/popularmaps : Most downloads based on daily average. A fairly good guide.
- https://lvlworld.com/featured : A list of older maps that have been "featured". Currently only maps from 2000 to 2010 are in this list.