The marquee player allowance.
Scrap it and raise the cap.
We don't want the best and brightest leaving the league. But RU and the NRL can offer more money (and prestige).
The cap is designed to keep things financially on a relatively level playing field. But as not all clubs are operating at or near to the cap, the financial playing field is currently not level anyway, regardless of the cap.
Want more excitement and box office players? Let the big clubs spend their money, to bring in (and keep) quality players into the league.
The marquee player rule doesn't work. There are probably fewer than 5 marquee players in SL, of an available 24 slots.
The signing of Tomkins and Sandow show how it should work. But both clubs could probably have signed those players regardless of the marquee rule. Tomkins wanted to come home, and Sandow was in exile. It just gave the players more licence to demand more money, as they knew any more they asked for didn't count towards the cap. It put the clubs in a worse negotiating position, most likely costing them more than if the rule didn't exist.
George Williams is not a marquee player. Wigan had to use their one remaining slot to keep a young player with potential. They've kept an existing player, who again was in a strong bargaining position due to the vacant slot, who's cost them a lot more in wages than if the marquee slots didn't exist. They're actually worse off for it.
I think you'll see those slots being used by the big clubs more to juggle more cap room anyway by adding their current players in order to take part of their existing wage off the cap, rather than being used to attract top talent to the league.
I'm yet to see the marquee rule make a real difference to the players in or out.
Raise the cap, scrap marquee, allow clubs to pay top players their market value - given the "market" contains two other leagues that can pay bang average players far more.