all 3 are in completely different leagues.

The Sea Pro is a no frills entry level boat, think old Trophy, WAC style where you dont have much fishing space once you put 3-4 guys in the boat. They get the job done, can accomodate usually 2 for overnighters in the cuddys. They dont make a hard top, so the only option for shelter is usually eisenglass/plastic. Which just suck in the cold wet rainy mornings. Seating is for 2 under the shelter, and anyone else is gonna be wet.

A grady will be the best riding of the 3 but suffers the same as the Seapro in fishing space, until you get up to the 25+ footers. Same deal as above; dry seating is lacking. Fit and finish is way better, its a solid and well built boat. The problem here is your price range. You most likely will only find a few for what you want to spend, and they will most likely have 2 strokes w/ lots of hours and be from the east coast..

Then theres the Parker. No frills meat and potato boats. Most are hardtops, which is hard to beat for the NW climate. They make 2 different hulls. One is a DV and one is a shallow V. You only want to consider the Deep V. The helm is forward on the Parker, making the ride feel more harsh than a WAC boat. But with it comes the trade off. The Fishing Cockpit is really big. Especially on the models like the 2320 which has a OS Bracket. you can easily put 5-6 guys on the deck fishing..
Its very utilitarian, smallish cuddy that would be really tight for 2 guys. There is Dry seating for 3 (very tight for 4) inside the standard Pilothouse.

So at the end of they day you are going to have to decide on what is important to you.. Do you want lots of fishing space, or a boat that lacks space but rides nice ?? It really comes down to how and where you are going to use the boat..

For me, I'll sacrifice some ride quality to gain fishing space. But after owning several boats over the past 10 years. I dont think I'll ever be able to go back to a boat with canvas for use on the sound or out in the ocean. Sitting in a bone dry cabin when its pissin sideways outside is awesome...

If Grady ever made a pilothouse thats what I'd have!!