I've done 1 lvl dips with:
- Bard
For Healing Word which I lack in Ranger or Paladin. Compared to Cleric gives extra skill
- Rogue
For having 4 skills, including 2 with Expertise. Expert Decpetion/Persuasion or Sleigh of Hand are good for any other class

- Ranger
4 skills, all weapons and armour (Ranger Knight), possible 5th skill - Sleigh of Hand Proficiency. Although enormous temptation for 2nd lvl because Fighting Style
- Warlock
Eldritch Knight to open i.e. blast doors with Eldritch Blast without having to swap weapons :P
- Cleric
for flavour, i.e. having my Good Drw/Half-Drow start as Eilistraee Clergy before moving into Paladin or Bard of Valor