My #1 lube recommendation is always Sliquid. It’s one of the only companies that makes vagina-safe lube.
For a regular, everyday lube, try Sassy, H2O, or Organics Gel.
For a delicious, vagina-safe flavored option, try their Swirl formulation – my favorite flavor is pink lemonade but they also have other options like green apple and cherry vanilla.
For sensation lubes, there’s Sizzle (warming) or O Gel (tingling).
I can’t tell you what’ll be most pleasurable for your boyfriend because it varies widely from person to person. If you want to try out a bunch of options for a lower price, you could get the Sliquid sampler set.