Vimms lair is a good choice, though i don't think they're in .chd by default, rather just .iso, or a compressed .iso format. It's highly consistent in naming conventions, and has a pretty damn near full collection. Main downside is limited downloading speed, and no concurrent downloads, but if you're just looking to download games you're interested in and not every ps1 game, it should be fine
yea, that's what I've been using so far, but the individual downloads + converting them has been a bit annoying, hence why I was looking for a way to eliminate a few steps from the workflow.