I've recently become a bit of an Eheim convert, but mostly because a LFS was blowing out their stock of Eccos. Honestly, either one works, especially if you are looking at one of the more versatile HOBs like the AquaClear or Tidal. I'd much rather go with a canister at the size of tank you are looking at, though.
For me, the HOB offers up the promise of not requiring too much extra footprint. It adds some depth or width to the tank's footprint, but doesn't need space in or near the stand in the same way a canister does, and it doesn't need to be on a shelf or floor. But the Canister has more flexibility in where you can store it, meaning it is easier to hide. And the larger the tank you are working with, the larger the stand, and the more likely you have a good place to hide a canister. You also get more options for dispersing flow for fish that don't like faster moving water. Lily pipes, spray bars, and so on. Fewer options for directing and baffling output from a HOB if you need it.
Personally, I think I still like HOBs on small (under 20g) tanks in the general case, since those are more likely to be in places like dressers, bookshelves, and the like. Except if I have something like a dedicated stand, or I'm trying to put together a rimless tank where a HOB just looks weird.
I'm going Eheim classic when I do the new tank. Need to decide on the size...since I'm going to run the inline stuff I'll probably need to upsize. Maybe the 2215 on my 32g tank?
I'm running an Ecco 2236 on my 23g now, and it has a similar rated flow rate to the Classic 2215. I do have to throttle it and use something to disperse the flow, but I'm also trying to keep the flow slow for the fish. It should be fine for a 32g, I'd think. Assuming you aren't trying to use the filter to create strong currents, anyhow.