I've found that wearing raw selvage denim without washing, the jeans tend to stretch out width-wise and eventually shrink length-wise after the first wash. So if you want a slimmer in the long run, you'd want the jeans to be pretty tight and a little on the long side. When I got my most recent pair I couldn't even get the top button closed, but after a few weeks they fit perfectly.
The general wisdom of sizing down is a bit misleading. Different brands size their jeans differently (a 3sixteen size 32 measures 33 at waist, whereas "true sizing" refers to a size being the same as its waist measurement), so the best thing to do is take your own measurements, or measure your best fitting jeans and check each brand's sizing table. Then get whichever size measures 1 or 2" below your actual waist size if you want your slim fit to stay slim.
If you're willing to pay $180-$250, I'd recommend you check out the selvage jeans
at Nama Denim. These guys are still relatively small but that means they have the time to respond and answer any questions you have about fit or anything else.
I think the lower prices are pretty covered... Naked and Famous for $140+, Unbranded $79+, Uniqlo for cheaper... At the lower ends you're just paying for the "selvage" name, but missing out on the quality stitching, heavier weight denim, higher quality fades from better indigo dye.