WDW Vet (many, many trips) heading out for our third DL visit in February. We played this game in the car over the holidays while traveling, and I'll give you my list. I won't include Fantasmic since it's closed for the next year plus - and I didn't include Paint the Night/
Disneyland Forever because I haven't seen them. What I am looking at is as a WDW regular - what makes Disneyland special. For example, Haunted Mansion is one of my all-time favorites, but it is not significantly different at DLR vs WDW (unless you are going when Haunted Mansion Holiday is going on) - so if you missed riding it you wouldn't be missing much.
DLR
1) Pirates of the Carribean - the only problem with riding it here is that the WDW version will never seem quite as nice as it did.
2) Indiana Jones - way better than Dinosaur. WAAAY better.
3) Space Mountain - Completely different from the MK one - and way better.
4) Matterhorn - Not the greatest roller coaster ever - I like BTMRR better - but it's the ORIGINAL Disney coaster and should NOT be missed.
5) The Fantasyland Dark rides (Alice in Wonderland / Mr. Toad / Snow White / Pinocchio / Peter Pan) - Only Peter Pan has a match at MK and is still worth a ride. The other 4 are now unique to DLR and so classic.
DCA
1) Radiator Spring Racers / Carsland - OK I'm already cheating with my #1. Experiencing Carsland is an important part of that park - but the ride is a must-do. It is my favorite ride in a US Disney Park - period.
2) World Of Color - this show is so amazing. Best show in a US Disney Park. Just so you know - these two experiences alone justify to me a first-time trip to DLR.
DCA drops off a LOT after these two...even with all the improvements there - but to get to 5.
3) Grizzly River Run - SOOOO much better than Kali it isn't even funny. Prepare to be wet though.
4) California Screamin' - an honest-to-goodness THRILL coaster in a Disney Park. It's so great - but you better like coasters.
5) Clarabelle's for a hand-made ice cream bar with your choice of toppings. DW reminded me of this when we were listing favorite foods. Since I couldn't come up with 5 attractions in DCA worthy of ranking this high.