My thoughts:
I own a 305 Express and I love the boat. My good friend in the berth next to me owns a 30 Marlin and we take turns venturing out on both boats. They share the same hull, but many characteristics are different. If I fished only, I would prefer the Marlin for its extra spacious cockpit area. But for cruising and fishing, I prefer the 305 Express. The larger helm area allows for 2 couples to sit comfortably while cruising and talking, especially in chillier weather up here in Maine. The hardtop is much larger allowing for me to store up to 6 fishing rods on the underside of the hardtop, freeing up cabin space. I can also fit 5 to 6 life jackets in the netting. As mentioned above, I also prefer the center helm sitting and the powered electronics box. In other posts on this site, I have shown photos of my setup when entertaining on the dock. I remove the helm chair and replace it with a nice table, making the helm area more usable.