For me, the following are canon:
TOS; TAS (but it doesn't have to be); TMP; TWOK; TSFS; TVH; TUC [TFF didn't happen]
TNG TV eps only -- NO TNG MOVIES! That story ends with "All Good Things". Kirk is alive and well in the 23rd century, sending holo-messages each year for Spock's birthday.
DS9; VOY -- I had Trek fatigue by this point, so I lost touch with the stories. They can be canon, but don't have to be.
ENT -- NOT CANON. The worst of the bunch, retconning or changing much of the established franchise history. The "Klingon mutation virus" is
definitely not canon! I'm happy for every episode to be one of Riker's holo-porns.
Post-VOY (e.g. Novelverse): I don't know much about them beyond stuff I read online, but I like the idea that the 1701-D crew has moved on and continue their adventures. Canon is OK!
JJ-Trek: Canon alternate universe. I like them. The model of the NX-01 on Marcus' desk is just a kitbash he made, not a real ship!