After replaying both Mega Man X collections, my opinions have changed.
Here are my most favorite to least favorite list.
Original: X1, X4, X2, X3, X8, X5, X6, X7.
Now: X4, X3, X1, X2, X5, X8, X7, X6.
The reason I put X6 last is because of the awful level design for example. The nightmare system made it worse. X7 is bad yes, but I thought it was a boring type of bad. X6 is a game that is a frustrating type of bad. I know the X collections have Rookie Hunter Mode but I still wanted to bring it up.