Of all the people listed it's

Lewis. Not hate, just 'like the least' as described in the thread title. He has a "secret" relationship (that everyone knows about) with someone who's:
unmarried (as far as we know?)
So what's the problem with

Marnie and Lewis just having a regular relationship? Nobody's ever mentioned a Mr. Marnie or a Mrs. Lewis so just enjoy each other's company out in the open! It's gotta be a Lewis thing, like it's more exciting to him to have an imaginary illicit relationship. But this has been discussed to death in loads of places sooo...
Among the people
not mentioned here it goes either to (1)

Pierre for lying about reselling the Farmer's goods and trying to hike the price of produce and sell it as organic or whatever to make bank. You sir can exit my field of view, and

Caroline already knows I'd be a much better spouse as she's the first person I befriend in the game.
Nooooo, not
only because of
Tea Saplings. Green hair is the best... uh, I'm sure lots of other reasons too. Yeah I'll get back to you...
And (2)

Rasmodius is the other. Trying to seem impressive by zapping himself out of the room when you first meet, only for the Farmer to find out they can buy a similar Stick of Everyday Zappitude from Krobus for the low, low price of 2 Cellars of
Wine. This guy went to Wizard Correspondence School for the purpose of learning levitation just to keep his decrepit old Silo-to-teetering-Wizard-Tower conversion home from collapsing into the pile of rubble that this ex-building has long yearned to end it's existence as. And only took that location as Lewis gave it to him tax-free on the understanding that instead of needing to spend
Pelican Town tax g
Solid Gold Lewis statue g on razing the Valley's biggest health hazard, ol' Razzie would fix it up to local standards. How many times do you think Lewis has checked to make sure? Yeah, you know. The
junimos know this charlatan all to well and simply refuse to speak to him, but on first meeting with the Farmer after they find that the Wiz tried to poison her with a stanky fetid stew of boiled newt nostrils and vole earlobes, they speak only with her. There's a hint there. All that before even mentioning the not-very-subtle hints of Valley homewrecking ol' Pointy-Beard is implicated in...