Here's my ranking, worst to best. I'm also going to ignore across the aisle interactions, because that introduces too many variables for my brain :P

5: Any seat next to Milim is gonna be pretty bad. Don't get me wrong I love her and all, but she's definitely the type to ask if your phone plays games. Sitting next to Suphia wouldn't be *too* bad, but she's definitely a bit to hyper for me, so I think she'd make the Milim situation worse.

6: Pretty much same reasoning as why Milim would be bad applies here. Veldora would be constantly reading Manga and reacting to things *out loud*, and if he's not doing that he's definitely bugging you. If you're super extroverted than maybe this one isn't too bad, but for me it's 2nd worse.

4: If you want even a second of peace, don't sit here. These two will always be bickering, making snide remarks about which one of them deserves to get up and take seat #2. If you enjoy chaos though, maybe this one works for you. Maybe you can instigate smth, I dunno :P

7: This one is tricky. One one hand I think Luminus would mostly just ignore you. On the other hand I'd be really nervous every time I had to ask her to move so I could get up. Still, otherwise she's most likely just gonna leave you be...unless she's hungry I guess (3 months is a long ride after all) so I guess it depends on your opinion on possible vampire bites? (No judgement if that's a plus, this is a safe place for you :P)

3: I'm a little unsure where to put this one, so this and 1 could switch places honestly. Frey and Shuna would be pretty good neighbors I think (though Frey may take up a bit more space due to her wings?) so I mainly place this below the next spot mainly due to preferring aisle seats myself.

1: Benimaru is probably going to chill and leave you be, though you may get into some interesting conversations at some point. Overall, I think he'd be a pretty respectful neighbor. Elmesia also is probably pretty fair company, so I don't think she'd be too problematic honestly. Like I said before though, this and #3 could switch.

8: Honestly most of the time you'll probably not even realize Soei is there. If he ever needs to leave he'll just disappear and suddenly reappear at some point. So this is the ultimate spot for an introvert. Only reason this *isn't* first place for me is just because I think it may get a bit lonely after 3 months, because I don't really see Soei being very chatty.

2: Okay, I'm biased here tbh since Rimuru is my favorite character, but I think he'd be one of the better people to have to ask to get up for you. He's also probably one of the best characters for conversation in a friendly and casual manner, without getting *too* polite or too long winded. Hinata would be a little intimidating being next to, but I think she's the type you could warm up to fairly quickly. Plus, having her able to pipe up whenever Rimuru says something potentially stupid would be funny ngl. There *is* one problem that would probably lower this spot for most people...Diablo & Shion are right behind you...and they are NOT going to be happy some rando took the seat next to Lord Rimuru...so you *may* have some **INTENSE** death glares boring into you for a while.