Harry Kim, by far. First, as noted, he used the Sikaran projector to get to Alastria, but it often seemed like he was one of the few to get home in many alternate realities. Like a cockroach, he's a survivor.
* He disappears through a vacuole and is replaced with a corpse ("Emanation"). He comes back mummified. Ensign Kharis? I'm surprised the crew noticed so fast.
* Slipstream riding the rapids ("Timeless")- only he survives along with Chakotay.
* Double Voyager ("Deadlock")- he gets killed, but finds a way to survive through a duplicate. In fact, he and Naomi Wildman can be considered to be the only 2 "original" people on Voyager. To quote the Romulan Senator from "In the Pale Moonlight", everyone else "is a faaaaaake".
* Hirogen takeover of the ship. Everyone else gets hunted while he gets immunity as the Scotty for the ship fixing it up whenever they break something.
* Jello Voyager ("Course: Oblivion")- His Silverblood mimic copies him quite accurately, making him among the last survivors. Seven has the excuse of imitation nanoprobes, but she was looking pretty green and sickly compared to Kim. Then again, Harry Kim was the founder of their race as a sentient race.
And he got home to Earth first, by stumbling across the Timestream ("Non Sequitur") that took him back to Earth.
And while he faced some danger (held hostage in a different state of matter by protostar creatures AKA Grendel, held hostage by a clown and turned into a baby briefly, sentenced to prison for a crime he did not commit [who is he, Chief O'Brien?], Tuvok steals his girl, every cute girl he knows dies except for the Delaney Sisters), he didn't get put through the ringer like some other crewmembers did (like turned into a transwarp salamander, driven insane, brainwashed, merged with Neelix, becoming Mr. Hyde, being subjected to Srivani experiments, getting a giant critter attached to you), though he did contract a few space STDs ("Favorite Son", "The Disease") and a nasty fungal infection ("Scorpion").