OP:
There are some things you haven't told us.
Most importantly -- do you have an external backup drive?
If so, what KIND of backup is on it?
Time machine? CarbonCopyCloner? SuperDuper? Something else...?
What OS are you currently using?
Could you name some of the most important apps you use?
What I'd suggest:
Migration assistant will "bring over" 3rd party apps, BUT because of "the age difference" some of the 3rd party apps you're using may no longer run.
You'll either have to update them, or (if no update is available) look for replacements.
Again, can't answer this without knowing WHAT you use.
How I would recommend doing it.
1. Create an external backup using either CarbonCopyCloner or SuperDuper.
If you've never used either of these, I recommend SuperDuper because it's so easy to understand and use for someone who's just downloaded it.
You can download it by clicking this URL:
SuperDuper is FREE to use for doing what we need to do.
Let SD create a "cloned" backup of your current Mac setup.
2. When the new Mac arrives, take it out of the box and set it up.
DO NOT PRESS THE POWER ON BUTTON or open the lid yet.
3. Connect the cloned backup. NOW power up the new Mac.
4. Begin setup. When setup assistant asks if you want to migrate from another drive, YES, you do.
So... "point the way" to the cloned backup and give SA time to "digest" everything.
5. Setup assistant will present you with a list of stuff that can be migrated:
accounts
applications
settings
data
I suggest that you UNCHECK applications, but migrate everything else.
Then turn SA loose and let it do its thing.
When done, you should be able to log into your "old" account, just as before.
Now, it's time to think about migrating apps.
But... how to tell what runs, and what doesn't ???
This may be easy BECAUSE we previously created a CLONED backup which (unlike time machine) can be mounted "right in the finder".
So... I suggest you open the cloned backup and go to the applications folder.
Start "working your way through" the 3rd party apps.
Double-click on them and see if they'll launch and run (even though they're still on the backup drive).
If the apps you want to migrate run without problems, I'll reckon that you can just copy them to your applications folder on the new Mac.
They should STILL run because you already migrated your "settings" using setup assistant.
That's what I'd try.
Again, "the key" to the above scenario is having a CLONED backup, not a tm backup.
Good luck.