Magic Kingdom has a lot to offer, including a long wait for the Seven Dwarfs Mine Ride but honestly, you will be happier waiting for Thunder Mountain Railroad.
In some ways, the attractions are similar in theme. One is a mine ride through a mountain a runaway train and the other is a mine ride that takes you into the gem world of the Seven Dwarfs. One is actually quite fun and the other is quite boring.
It's hard not to be enamored with the wonderful themed appearance of the Dwarf's Mine Ride. The outside sets are really nice and when you see the mine cars roar by you with smiling faces, the nearly 2-hour wait sometimes calls to you. Quick, can we get a "lightning lane" pass for this as we scramble to open our Disney Parks app?
Save your money and your time, go to Frontierland and ride Thunder Mountain Railroad.
Comparing the two shouldn't extend beyond the coaster itself. Seven Dwarf's is a smooth coaster that uses interesting tech allowing the rather surprisingly uncomfortable cars to sway back and forth as you go. That is about the only thing redeemable about this attraction.
By the time you hit the first hill, you're about done. The ride is super quick and you are left with a "I waited two hours for that" or a "I can't believe I paid for this." Sorry, but it is true. I have yet to talk to one person who said the ride was enjoyable and something they would ride again.
To my surprise, TMR is a lot longer, with more twists and turns and ups and downs. The aesthetics are fun and detailed and even the stand-by lane isn't boring. The ride doesn't sway back and forth and the only downside I can find is that the front car view is blocked by the train engine.
Wait time will vary throughout the day but at the most a 90-minute wait on the days we have been there. Most of the time, we tend to see 55 minutes or 70 minute highs but personally, I would wait 55 minutes to ride TMR before I would wait 45 for Seven Dwarfs.
I know it's hard to believe one person's perspective and opinion but my 5-year old who has discovered adrenaline since he became tall enough to ride rollercoasters has made it clear he will not ride Seven Dwarfs again, in fact, he won't ride Slinky Dog either. Thunder Mountain Railroad and Guardians of the Galaxy...sign him up all day long!