I grew up going to Disneyland, so to me, that is still my favorite, special place. However, I have also been to Disney World a few times, and it is also amazing, with lots of different experiences to offer. There are many things at Disney World that you cannot see at the Disneyland resort - certain rides have better cues or buildings, and of course, there are the different lands like Animal Kingdom.
But for me, the magic of Disneyland is that 1)this is where it all started! This is where Walt build his dream! 2) Yes, it is smaller, but that is part of the charm. It doesn't take you almost an hour to go from one park to another, you don't have to take a bus, and it's easier to maneuver. 3) The special, unique parts of Disneyland resort must be appreciated for what they are - Small World is a much better outer building, Indiana Jones is great, and World of Color is incredible.
You have to look at each experience as individual. I went to Disney World shortly after it opened, and I was very disappointed. I told my parents ""It's just Disneyland with a lot more walking!" Of course, that was LONG ago. I have since been back numerous times, and I love Walt Disney World for all of the unique things that have been build over the years - the Haunted Mansion building, cue and ride is amazing, the Pirates of the Caribbean cue is great, Tower of Terror is longer, more surprising. BUT there is no place as cozy, historical, and special as the original Disneyland. And with smaller kids, there is a GREAT advantage in not having to walk as much, especially if you stay somewhere close so you can easily go back to your room and rest. It's MUCH easier at the Disneyland Resort. Have a wonderful trip