I, too, prefer no cap, but if I had to choose then it?d be the NBA model which has some hard cap provisions built in. In addition to the luxury tax, there is also this:
2. Certain components of the NBA's system function as a hard cap under specific circumstances.
20. Further restrictions kick-in once a team crosses a point known as the Apron. In 2017-18 the Apron is the point $6 million above the tax threshold. In subsequent seasons the Apron rises or falls by one-half the percentage that the salary cap rises or falls.
Here are the tax and Apron amounts in each season:
Season Tax Level Apron
2017-18 $119,266,000 $125,266,000
2018-19 $123,733,000 $129,817,000
In other words, when a team is below the Apron and uses its Bi-Annual exception, receives a player who is signed-and-traded, or uses its Mid-Level exception to sign a player to a contract larger than allowed by the Taxpayer Mid-Level exception, the team becomes hard-capped at the Apron for the remainder of that season. This eliminates any potential loophole where a team could first use one of these exceptions and subsequently add salary to go above the Apron, since the reverse -- adding salary first and then using the exception -- would be illegal.
If a team is hard-capped, it cannot exceed the Apron under any circumstance. If the team subsequently needs to sign a player (for example, to replace injured players) it must first create room under the Apron by waiving player(s) with non-guaranteed salary, waiving player(s) with guaranteed salary and utilizing the stretch provision, trading downward in salary, etc. A team that is hard-capped can sign players to non-guaranteed contracts for training camp or the regular season, but must rid themselves of such players before their salary would take the team above the Apron.
A team subject to the hard cap can also sign players to Rest-of-Season contracts during the season, as long as the salary pro-ration keeps the team below the Apron.
25. Exceptions explained
http://www.cbafaq.com/salarycap.htm