Transfer to new iMac

The only items that you do not need or want could be the old 32 bit apps.but even if this gets transferred you can delete from the app folder later (they will have a line through them). I have never excluded anything in the past and all was fine using Migration Assistant.

Below are instructions for the most reliable and overall fastest method to migration. I strongly recommend that you follow them to the letter.

Please use the steps as outlined in Setup Assistant and Migration Assistant. If you do not have a Time Machine backup, then make one! If you do not know how please refer to Back up your Mac with Time Machine which only requires an External Hard Disk, if you need a External Hard Disk many experiences users on these forums prefer the OWC Mercury Elite Pro due to it's reasonable cost, high level of reliability and ease of service. You can use the drive with the new Mac to backup when you are done migrating. 

I second the comments above. I have also always transferred everything with a complete success. However, some people prefer to not transfer their apps and then reinstall them into the new computer. The other thing to know is that for each group of transfers it's all or none. You can not individually select. Enjoy your new Mac.