For ukulele I use two types, planetary geared pegs and miniature slab headstock tuners.
The planetary pegs are either metal mini-banjo style or Peghed planetary pegs, which look just like ebony wooden pegs. I use the pegheds mainly on sopranos but will use the metal planetary pegs on all sizes if requested.
The mini guitar-type tuners are high quality open-geared units. The most important considerations are tuning accuracy and light weight, especially for 5, 5 and 8 string headstocks.