Hi Kit-e
We have two sit-on kayaks. We tested lots of different sorts before we bought them. Our local kayak shop has regular "have a go" days on the river where you can go and paddle different types - I think you'll find most kayak shops do this locally and is worth checking out.
The brand we have is "Ocean Kayak - Prowler 13". Although initially we used them for fishing a lot (ocean, river and estuary) we have found we use them more now for fitness and sightseeing. So, our choice was good in that they aren't as wide as some of the big fishing kayaks, but have good tracking (one paddle stroke gets you a fair distance and they maintain their course) and cut through ocean chop quite well. They also have a rudder operated by foot pedals.
We have the back rests which also include a padded seat. Under the seat we have put some high density foam (like the blue foam roll-out camp mats, approx 15mm thick) which makes the seat much more comfy if you are out for a whole day. If you know you will be paddling in calm water, you can put foam rubber stoppers/bungs into the drainage holes and it stops any water coming back up - but we have found you're better off to not use them as you do get a few splashes from your paddle that can easily drain away if the drainage holes are clear.
Our kayaks have a small, secure hatch in the centre with a screw top lid but we also use an aqua-pack to keep phones and keys etc safe inside this hatch. There is a main hatch at the front where we store flares, torch, spare rope and emergency paddle. At the back is an open rear well and we put soft eskies in here with ice or water to put the catch in.
If you are planning on doing lots of fishing, I would definitely recommend something like the Hobie as they are wider, more stable and if you can move using your feet rather than a paddle, you will have hands free for fishing rods. We have found juggling rods and paddles a PITA at times. If you're in calm water and happy to drift, no problem, but if you want to trawl or maintain a position in a current, it's hard without putting down your fishing rod, picking up the paddle, paddling for a bit, then swapping back to the fishing rod - if you see what I mean.
We have rigged up little anchor trollies on our kayaks - which means we can anchor from the front or rear of the kayak depending on which way you want to face and fish. We put a float on the top of the anchor line and then clip that with a caribiner to the anchor rope. This means if you catch a big fish and want to tow around for a bit, you can easily and quickly unhook from your anchor, go chase your fish, and then come back to your anchor. Or if you get a big fish aboard the kayak and start squealing like a girl, your husband (or BF) can unclip from his anchor, paddle over, and help take control of the birds nest of fishing line... (My husband has to deal with this issue quite a bit...)
Also, with the anchor you can stop, jump over with your mask & snorkel, explore around and then come back to your kayak.
Edit: In winter, we wear "Sharkskin" wetsuit pants - they are made for paddling which means they are a bit higher at the back so when you sit down, your lower back is still covered and warm. The inside is like polar fleece and the outside is wetsuit. And we wear wetsuit booties. All toasty warm
Hope this helps.
