The very best effects I have had myself and have seen to be effective in other families is to keep my own attitude toward chores cheerful. With my daughter and now again with my 4yo. grandboy, I assisted with the chores while they were young, singing and making games out of them, admiring our results and congratulating each other for a job well-done. And I would take pleasure in my own work, and satisfaction in the results.
That's a much more worthwhile "treat" than a material reward, but I think the occasional treat, family game night, dessert, or small payment for a job over and above regular chores is probably appropriate. Avoid "bribe" language, though, such as "I'll give you a goody IF you do this chore." That puts too much manipulative power into a child's hands, and kids don't have the restraint not to use that power.
My daughter became more grudging about keeping her room clean in her teens, and I pretty much allowed it, but didn't step in to keep her clothing wearable. That was completely up to her, and she always did at least minimally as much as needed. As long as she wasn't attracting vermin, she was old enough to assume that particular responsibility, or not.
But her years of passive resistance have long since passed, and she's a much better housekeeper than I am. And her son is on track for his age, cooperative and becoming more capable by the week.