Larry Renger asked approximately the same question a couple of years ago. Here's an updated version of what I told him then after I bought a 2004 Odyssey:
Minivans are made with hauling kids in mind. The Toyota is probably even more kid-oriented than the Honda. To get the options I wanted in the Toyota, I'd have had to buy a lot of stuff for the nonexistant kids: side airbags in the back, for example. The Honda has a rear air conditioning system, so I can keep the planes cool. I got the Honda because Consumer Reports said that it's good and it meets the 4x8-sheet-of-plywood criterion. I've had two Plymouth Voyagers before, and I like the Plymouths better. The Honda is designed for people less than 5' 4" tall. My main complaint about the Honda is that I can't put my leg in the requisite positions to accommodate my bad left knee. I was pretty crippled after the 2004 Nats trip. Since then I found a fancy foam pillow that holds my leg in an acceptable position. I drove to Muncie and back three more times without ill effect.
Other things I like less about the 2004 Honda than the 1995 Plymouth:
The Honda has two electric side doors. This is, I think, really silly, and it's dangerous. My wife hit the button to open the left side door when we arrived for a coaching session in Salem. The door crushed a stunt plane. It takes far longer to open or close one of these doors than it takes to open or close the manual Plymouth door, and it is more difficult to do. The remote device makes it worse. It requires a certain button push sequence, and it still takes several attempts to open the door. The door will work manually-- you can turn the power off-- but the motor spins and sounds unhappy. Eventually, when I need to get inside the doors for something, I shall take the motors out, but I resent having paid for them. The 1995 Plymouth has one side door, which is sufficient.
The Honda floor is not level. It has lumps where the seats mount. When the seats are out, if you put something just inside the door, it will fall out.
The rear seat on the Plymouth can be removed. I removed it when I bought it, and it has been in the attic ever since. It can be installed rapidly if I ever need it. The Honda seat folds into the floor. It looks like it can be unbolted to leave a nice well for fuel cans and toolboxes, but because the floor around the well is at different levels, and there is no floor behind the well, there is is no good way to mount a cover for the well.
The Plymouth, having no well for the rear seat, accommodates a full-size spare tire under the floor. The Honda has a dinky temporary spare in a well behind the front passenger seat. It would require some serious unloading of cargo if there were a flat on the way to a contest.
Both vans have electrically actuated rear windows, hinged at the front. These provide nice ventilation. The Honda's switches are on the driver's armrest, whereas the Plymouth's are overhead, and accessible to both people in the front seat and also the people (if any) on the second row.
The Honda 12V outlet is inconveniently located on the floor, and turns off when the ignition is off, making it difficult to charge batteries and requiring me to put my GPS on standby power whenever I stop the car.
The Honda dash has a hump in front of the driver, making it difficult to mount the GPS.
The Plymouth shifter has a detent at Drive, so you can shift into Drive without looking; the Honda does not. You gotta check to see if you hit the right gear. Sometimes I drive in third by mistake.
My Impact and canopy fit in the Plymouth. I had to build a new plane holder to fit both the plane and canopy into the Honda. Both vans accommodate a 4 x 8 sheet of plywood, but above the floor the Honda is narrower than the Plymouth.
The Plymouth oil filter is accessible without putting the car on a lift. I had to buy new, special ramps to raise the Honda to get at the oil filter.
The Plymouth oil drains without much mess. Honda oil is very thin: 5W-something. There is a lot of head on the oil pan. When you remove the plug, which is on the aft end of the oil pan, the oil gushes aft. When you remove the oil filter after having drained the pan, about a quart of oil gushes out onto the car structure. There is no clear path for it to drain.
The Plymouth has a space between the front seats where one can put a basket to hold tapes, food, and other essentials. The Honda has an obtrusive folding table that occupies as much space, but offers less storage. Only when the table is up can a basket fit between the seats, but the table prevents basket access.
The Plymouth has reasonable armrests. The inboard Honda armrests are dinky. The outboard armrests do not go far enough aft, and are at a different height than the inboards. You won't like it if your arms are the same length.
The Plymouth has a light under the hood. Not so the Honda.
Chrysler allowed the Plymouth software guys to spend about the right amount of time thinking up the door lock logic. The Honda guys had too much time and too little supervision. The Honda doors, if unlocked by the remote device, relock themselves if you don't open the door immediately. There is a sequence that sets off the alarm when you lock the doors and then open a door from the inside. This resulted in our spending some time with a very nice police officer in Minneapolis on the way home from the Nats. I imagine the Honda people as living in Tokyo and not having much experience operating automobiles.
The Plymouth's rear-window defroster shuts off after the condensation is gone. The Honda's stays on.
The Honda's radio is inferior to that of the Plymouth.
The Honda's rear windows do not come down far enough to see the headlights of cars in the lane to the right at night. Changing lanes is dangerous.
Rain pools on the side window such that you can't see the outside mirror well. This is a problem in Seattle.
Things I like better about the Honda than the Plymouth:
The Honda has an annunciator that tells you when the cruise control is engaged. So does our 1991 Accord. I really like this. The Honda cruise control works all the way down to 25 mph; the Plymouth's only goes to 30.
The Honda has a CD player; the Plymouth has a tape player. There are some stereo system controls on the steering wheel.
The Honda's temperature control is better than the Plymouth's. The Plymouth has a manual, mechanical slide temperature control. The Honda has an electronic control that purports to be thermostatically controlled. The setpoint and the stable temperature are different and have an unpredictable relationship, but it actually works pretty well. It is not really automatic, but it is more stable than the Plymouth's system.
The Honda has an electrically adjustable seat, giving you a choice of many uncomfortable positions. My wife likes it.
The Honda cupholders are better and more numerous.
The Honda glove compartment locks. The Plymouth's doesn't, but the Plymouth has a lockable, unhandy drawer under the passenger's seat. The Honda has a dinky drawer under the passenger's seat. It has no detent in the open position.
The Honda has a second 12V outlet at the back of the cargo compartment. The Toyota has three 12V outlets and optional 115V outlets, although probably much costlier than an inverter.
The Honda accelerates faster than the Plymouth.
The Honda second-row seat attachment seems more secure than the Plymouth's.
The Honda has side airbags.
The Plymouth's visor is not long enough to keep the sun out of your eyes when the sun is to the side of the car. The Honda visor has an extension that solves this problem.
Features I wish the Honda had (and the 2005 does have, I think):
More driver legroom
Heated outside mirrors
Outside air temperature indicator