I have only been fishing for 16 months but being localish to Selsey have been to both West and East beaches and had good and bad sessions at both.
Fished low tide beside the lifeboat station and caught 29 small bream day time in June. But also blanked at same place 3 days later. Two weeks after that got into smoothhound, at the same spot, but the two hours up to high tide, in the dark, for a few sessions and caught my biggest ever fish, a starry smoothound of 12lbs. During three sessions at the end of June into July I caught six hounds got smashed at least ten times had four broken hooks and got wrapped around a groin twice. Learned a huge amount not least the importance of setting the drag appropriately, you can adjust it during the fight. All these fish took ragworm on a two hook flapper with fresh peeler crab on the other hook. I did change the position of the baits to see if it made a difference, but the fish still took the worms. I always thought hounds went for crab above all else!!
Other fishermen I have spoken to will contradict all I will say, I know because I have asked them and one guy says one thing and the next guy says the opposite. It must be down to their individual experiences.
But generally my best sessions have been at East beach but I have fished it more often. But having said that I have had two really good sessions at the extreme west end of West beach at night fishing the tide up to high and 1 hour past. Went with a mate and both of us caught over 30 fish each. Mostly pouting but with good whiting, that we kept, small bass, rockling and a small blonde ray.
Some people say Selsey fishes best at low water some say its best at high water, some say East beach is best others say West beach is best.
I think that they are all right, but not necessarily when I'm fishing there.
That's my experience of the place, I hope it helps, and I will certainly be going back many times this coming year. Sometimes it's great sometimes it's rubbish. Just like everywhere I suspect.