I vote Gnome but appreciate this is a toughie.
Or is it?
If you take Lucky away from Halflings you have a pretty vanilla race that is good at running between opponents' legs. But Lucky is pretty cool.
Against that, Gnomes have a free multi-utility cantrip Minor Illusion. Speak with Small Animals is really useful, and Proficiency on magic v mental stat saving throws is not to be sniffed at. The rock gnome tinker ability can be fun with some thought.
A white-labelled own brand version of Frodo is only really there due to the influence of LoTR; the Halfling really doesn't feature in any other literature whereas the Gnome is a thing. It's folkloric. They're featured in Alexander Pope, Nathaniel Hawthorne, CS Lewis and Terry Brooks...
"Gnome" is a name; "Halfling" is an epithet at best, a racial slur at worst.
Gnomes have more personality, and as Jules from Pulp Fiction would say, "personality goes a long way".
Vote Gnome. Vote for a world without shoddy rip-offs.