I mean, I'm also leaning more towards Lesnar/Strowman but it would be kinda weird if the Undertaker makes an appearance after a match that isn't the main event. With that being said, I wouldn't mind it being like that. You can still have a not-so-important match following the Taker segment and then still have people be excited for Lesnar/Strowman.
Also, old school rules would always suggest the title match to end the show and especially with a strong and popular champ like Lesnar I don't see any reason as to why he shouldn't end the show