My campaign has four tiers of rewards, as well as a bunch of milestones. It's neat to have milestones, since that gives you - and your backers - something concrete to strive towards.
1$ - gets people access to weekly sketchposts, in which I either post previews/sketchy excerpts from WIPs or behind-the-scenes development stuff, like environment sketches or character design. Also gives access to monthly Q&A-comics and sketch-comics in between chapters.
3$ - all of the above, as well as access to upcoming pages ahead of regular readers. Patreon-backers are usually two pages ahead of regular readers - so when regular readers read page 10, backers are already reading page 12, and so on.
5$ - all of the above, as well as access to PDF-downloads of all the comics and stuff I make that isn't Grassblades. I draw - and have drawn - a bunch of oneshot comics, one finished graphic novel, some illustrated stories, etc. New downloads are sent out as projects are completed. Upcoming stuff: my Inktober-story and Wishlight.
10$ - all of the above, as well as downloads of Grassblades-chapters as they are completed, in hi-res PDF format with a bunch of extra materials. Also grants access to extra giveaways (though I haven't had the opportunity to run many; I need to hit a milestone goal first, and get more organised).
Most of my backers are in the lower two tiers, for obvious reasons, but I do have backers spread out across all four tiers.
As a reader, I think early access to pages, as well as sketch-posts would be the main draws for me. But I'm sadly not really in a position, income-wise, to back anyone on Patreon regularly, so I haven't really had the opportunity to think about it. Though ultimately, I think I would choose to back people even if I didn't get any rewards - personally, enabling other creators to continue doing wha they're already doing is good enough for me.
But I'm aware not everyone feels the same way.