As with any other method. Most are difficult to get right like partial, hanging, charcoal, etc. etc. It's always something with any method. And uncomfortable tell me one method you consider comfortable. It's all about personal preferences.
None are completely comfortable, but my preference would be a shotgun powerful enough to blow my head off.
I know that's there's very little chance of survival and if I point it right I'm basically dead instantly.
Shotgun method is best method, besides perhaps assisted suicide in a professionally controlled environment.
So my preferences
1. Assisted suicide service
2. Shotgun blast to the head - Very quick, 99+% effective.
3. Pistol/Other guns
4. Train method - Unless you're retarded and decide you throw yourself under a slow train, this method is very effective. If you get the right train track and a fast enough train, if it hits you head on your basically instantly obliterated. People who fail to die have often tried to use this method in a ridiculously stupid way.
5. Jump - Find a cliff/building high enough - If you fall onto a hard rock/concrete surface from a high enough height, you're almost certainly dead. A few scary moments which you can manage through inebriation.
All of these are preferable to SN which makes you feel uncomfortable for potentially over 20 minutes and if you throw it up and mix the substances/drugs w/e wrong you are panic dialling emergency services to help you.
For me, it's the most accessible one, hence I am choosing to go with it.
Good luck.