@ColdBuffalo There are few things that you need to consider, before anyone can give you a precise solution:
1. What is the Content Volume (Size of Pages and Assets). Content Count can be 100 or 1000+, and the volume can still be MBs, which is manageable.
2. I am assuming both are AEM instances. Please add the type of AEM instances, for both Source and Destination (AEM On Prem, AMS, or AEMaaCS).
Based upon above information, we can suggest you :
a. Content packages - Package Manager
b. CTT tool
c. ACS tools
For Non AEM instances, solutions would be different