Promotion play-off final is without doubt the match which has the biggest impact to any club's financial future. The match with the biggest purse in world football.
Luton Town was non-league as recently as 2014 so it has been quite a rise for them. Last time they were in the top division in 1992.
Coventry hasn't been in the EPL since late 90s and was also recently (2018) as low as in League Two. So it is between two clubs who have turned their fortunes around in a remarkably short time.