Changing transmission fluid

When changing transmission fluid, is it better to drop the pan,or take it to a place that sucks it out and replaces the old with new?

The pan should be dropped and the contents inspected, and the filter changed. This does not change out all of the fluid, but if this is done every 30-40K (as it should be) then that won’t matter. A fluid exchange leaves your old filter in there.

You said nothing about this car, but if it’s gone way too long without transmission service you might think about dropping the pan, changing filter and THEN doing the fluid exchange. OR, do the pan/filter and then again in about 5K miles. OR, do the pan and install a drain plug if there isn’t one. Change the filter and then drain and refill a few times in relatively short succession.

You have a Honda and Honda specifically says to never take it to a place that sucks out the old and replaces with new. You must drain and refill and on a Honda, you absolutely must use only the Honda ATF. For more specific information, please list the year and number of miles on the vehicle and how often, if ever the transmission has been serviced.

BTW, unless it is a new model, the transmission does not have a pan. It only has a drain plug.

Honda Accord - I always forget to look for a tag.

Drop the pan and never do the flush, but Hondas have a drain plug. So on a Honda, you just drain the fluid and fill it again. The filter is internal and not normally serviced. Takes about 10 minutes but use only Honda fluid.