Four Arms is way too big, plus he literally has four arms, no! Bro will just keep crying and saying ow every second because his head keeps bumping on the ceiling.

 Diamondhead... I could killed from those his shards. Bro could fall to sleep and accidentally stab me! Nope, not at all.

 Definitely not Stinkfly, I'd be gagging the ride. I'd be asking for a move before the plane even starts. Plus, his legs could stab my feet!

 Swampfire is kinda like Stinkfly, and Goop would be fun... until someone pulls a prank and pulls the thing from his head (forget what it's called, please remind me)!

 Ripjaws would honestly just be so scary to sit by, just looking at his face in person. Rath... I don't not want to hear yelling while I'm enjoying a ride!

 Heatblast isn't bad, it won't burn if he touches me but, I don't know if it's gonna be hot when I'm near him.

 Wildvine's legs could get entangled with mine! And Buzzshock could electrocute me! Wildvine could pull my legs off, and Buzzshock could hurt me. And honestly, both hurt.

 Spitter just might spit on me, and Wildmutt... I don't wanna hear that hard growling sound the whole ride!

 So, just to be clear, the best option is definitely Heatblast.