What's your favorite reel seat for spinning rods freshwater 

Fuji DPSSD, the deluxe version of the DPS, size 17 (better than 16 for a long day's fishing) mounted up locking with a ramp of cork or rigid polyurethane off the front.  Feels great in the hand, nice and smooth off the front, no hands on the threads.  

Been doing the skeleton seats with the cork spacer between them lately for a couple customers. I like them. They are comfortable. I like to do hidden threads as well. Makes the grip look like one full piece with only the metal bands from the reel seat parts showing.

To me this is the most comfortable.

The aero seat is a favorite of mine. Standard uplocking also works well. 

I prefer Tennessee with rings.  Second is an Areo, but I like it installed uplocking.

 

There's a size 17 Fuji spiining seat in the middle of that cork. 

I buy th 17 mm Aero reel seat because it's more comfortable and all standard 1 inch + grip materials you'd use on a casting rod also fit inside.

3 hours ago, S Hovanec said:

but I like it installed uplocking.

With up locking you can make a small ramp off the front of the seat hood, same diameter as the hood or slightly smaller to facilitate finishing it if finishing is involved, and the transition from the seat to the blank is seamless.  Use a size 17 seat (straight, not aero) and the ergonomics are good.  Makes a very comfortable setup that is also very handsome.  

My all-time favorite is the Fuji DNPS 20, large enough in OD to be comfortable all day, long enough that I need no transition material, and down locking I have a smooth surface for my hand,  just plug the ends and go. 

If I'm using a full grip, I use the old Lew's reverse taper pattern.

Does anyone have a picture of an uplocking aero seat?  Thanks.

Take the picture of the Aero seat above and turn it upside down. The threads on the seat are the same as the Fuji seats, so if you want to hide the threads use one of the Fuji options like the HPS.

Fuji VSS up locking