Unless you have problems with your software Migration Assistant is easiest way to copy your data and settings to new Mac.
If it fails you can always copy your data manually.
This^^
A restore is that, a restore. Meaning what you had. It might not even be possible if your MBP models are different. Furthermore, if you had something going on that slowed you down, then restoring can end up restoring what slowed you down.
A "clean install" is rather a misnomer. If you mean a completely new installation, all applications installed from downloads or media, manually copying all user data, etc etc., then no, it's not worth the risk or the hassle, and it may do anything but speed things up. You might get rid of a kext or cache or pref that caused problems or slowdowns, but you might not. It's like having a problem with a car and just disassembling and reassembling it in hopes that it fixes the problem; better to diagnose the actual problem and fix that.
Unless you've got a good reason not to do what Apple's engineers recommend, just run setup assistant (which is what starts up when you start your new machine) and use TM or the old machine to migrate. It generally works flawlessly. And quickly.