TLDR: It dramatically varies per country based on other factors.
This question is impossible to answer accurately. I will do my best.
The question is loaded with a presumption that full voting rights between nations are equitable. They are not nearly similar enough without a more defined scope of the question to assist in defining what is considered "full voting rights".
A second issue is the question assumes that non-citizen's residents between nations are comparable. This is again not something that can be done without further clarification or definition. Just in North America between Canada, US, and Mexico there are issues comparing these.
My answer is addressing the underlying issue here. Voting rights and levels of citizenship represent degrees of trust and membership to a society. The varied level of power granted to foreigners depend on the culture of the host nation. The pros and cons for granting power to foreigners depends on the culture of the host nation as well, as it is largely influenced by the reasons for migration.
It is a matter of culture.
The core of this question lies at the heart of the culture of the community. Here, the communities are countries. To oversimplify this, every country has its own culture. This culture carries with it the concept of identity and sovereignty.
These communities have a culture with levels of welcomeness, agreeability, or general xenophobia based on generations of experiences. A prime example of probably the most xenophobic community in present-day is the Sentinelese, which likely has a cultural memory of xenophobia developed from having people kidnapped and then everyone dying of disease after that. I would love to hear the elders tell the tales of their people to know their perspective of what the British explorers did. This is a clear example of culture defining how influential the community wants outsiders.
Then you look at New Zealand. They are governed by settlers that conquered the land (you can argue using the word conquer but the indigenous Maori do not rule the land). They are an island nation with very strong natural borders, so they have little to worry about with unwanted people wandering in their borders and begin meddling. This strong natural border means more control can be done with who comes in, leaving less worry about the person once they are in.
This applies to the pros and cons as it pertains to how residents or citizens are viewed by the host community as members of the community.
Voting rights are basically the membership card to that community. It allows influence over that community that has lasting impact. The more capacity to vote, the more of a member.
Voting rights define the class of member a person is to a community.
From being a visitor with no say to being the leader of the entire community, every step of eligibility is like a degree/class/rank/level of member.
The definition of visitor, resident, resident-alien, citizen, etc. is a label to these levels of membership to the community.
Establishing what voting rights are to the community allows the pros and cons to be evaluated more appropriately.
Three primary factors are in play that influence this(in order of sentence length):
- How hard it is to obtain the voting rights.
- How much of a threat outsiders are perceived to be.
- How much interest there is to migrate to the community.
This is where the answer falls apart. The relative differences between those factors can make what would be a pro to a con. Given that the situation can change based on context, this type of question is best constrained to a debate on specific examples or countries.
Seeing how dramatically different the Sentinelese are from New Zealand highlights this.
Edit: Typo Edit 2: Illuminating comments added perspective.