Is the partial or night night method more reliable?
Part of the problem is there's really no way to do a comparison. So, all you're really going to get are opinions and anecdotes.
To kys well involves a lot of research, planning, prep, and practice. I think both of those methods can work well... if done correctly.
This site has tons of resources. I'd start by looking into the ~mainstream books that have been published (like the one I like, "Five Last Acts" and the "Peaceful Pill Handbook" (PPH or PPeH): These people have worked hard on this... kinda their full-time jobs. Also look at the "megathreads" for the methods you're interested in. This page indexes many of the resources... it's a long list, so please scroll down to see it all before diving-in. There's also a wiki to check out. Best wishes!
https://sanctioned-suicide.net/threads/suicide-resource-compilation.3/