The New Jersey Plan was proposed during the Constitutional Convention of 1787 as a response to the Virginia Plan. The New Jersey Plan favored a unicameral legislature with equal representation for each state, regardless of population size. This plan was favored by smaller states, which were concerned that their interests would be overshadowed by larger states with bigger populations.
In terms of excluding enslaved people from population counts, states with smaller populations or those with fewer enslaved individuals would have been more inclined to support such a measure, as it would prevent larger, slave-holding states from enhancing their representation in Congress.
Given these considerations, Rhode Island would likely prefer both the New Jersey Plan and the exclusion of enslaved people from population counts. As a small state, Rhode Island would benefit from equal representation and would not have a large population of enslaved individuals to count, thereby maintaining its relative influence without being overshadowed by larger states like Virginia.