The other answers discuss the linear/circular and how it plays with AF systems nicely. I wanted to chime in to talk about future proofing.

Having to rebuy the same equipment to fit your newer equipment is pointless. For example, if you did buy a 67mm filter to fit your 67mm lens, you'd be up a creek if you bought a fancy new wide angle lens that uses 72mm filters. (You would end up needing to buy another filter).

In order to future-proof, you'll want to take a look at your current lens line-up and any future lenses you might acquire (let's be realistic, yea?) and get the filter that will fit the largest one. Use Step Up rings for smaller lenses so that, ultimately, you only have to buy a single filter.

As for slim filters - I do believe they warrant consideration. Personally, I use the Formatt Hitech 100mm system on a Canon 16-35 f/4 for most of my landscapes. I get heavy vignetting at 16mm (full frame). Given it's a system, there's not much that I can do about it. But, you may run into a situation where a super wide lens vignettes a bit more with a Step Up Ring + Reg. Filter vs a Step Up Ring + Slim Filter. I'm not recommending you get a 100mm system - more so that, since you'll likely use step up rings, a slim filter may vignette less in this configuration - thus you have less work to do in post.

Also, keep in mind how often you'll put on and remove components. This additional wear-and-tear will be better combat by brass threaded rings and filters.