Favorite? Depends on the shot. Pure distance, it's a Destroyer. For holding a line into the wind, an Xcal. For long S curves or turnovers I use a Beast. For tomahawks and control drives under 300 or so, a leopard. For sidearm shots, I have been using a Groove. For wide open less than 250ish hyzer shots I use a roc. Around 200 ft I like to drive with an Aviar.
They're all my favorites, and I'd have to buy a new one if I ran out of any of those discs.
But I suppose if I had to pick just one to play a whole round with, it'd be my Leopard. The fact that it tomahawks so well and is such an accurate flier just give it a special place in my heart. It also is quite a floater so if you can find a tailwind it is easy to lob pretty high and expect to glide a lot. :) Really the only issue is shooting it into a headwind, in which case you have to be very careful with the disc to finesse it quite a bit and remember that it turns over very easily!
167 Champion Teebird; well any type of teebird really. They are very versitle. I currently have a 167 champ in my bag, 172 star and a 172 cfr TL. I found that they work well on almost any kind of drive.
overall id have to say my go to driver is the wraith i have a heavier star wraith(172) that i use for hyzers,i have a lighter beat in pro wraith(167) that works great for flip drives,and i had a midweight star(169) that was great for straight shots or a little flip sadly that disc was stolen from me right off the green while i was in a small lake retrieving my lighter wraith.i have replaced my 169 star wraith with a 167 star teerex it is very similar but less stable wish i would have gotten a heavier one
My go to driver is a millennium OLS, I carry four of them in different stages of wear. I don't have the arm speed to throw some of the faster stuff and I can get the OLS to do just about anything I need it to do.