SharePoint template choosing for assets tracking solution

Vaidas, it sounds like if I were you I would invest a little more time into the requirements of the business process you are trying to resolve.  As you state and like most things Microsoft, there are multiple ways to solve a given requirement, either wholly or using a combination of tools. 

You list multiple different sites of different types.  First you need to understand the difference between "classic sites" (Team, Document Center, Records Center) and "modern sites" (Team and Communication sites).  For classic sites, they are just a regular site that has been pre-configured targeting a specific purpose with certain features activated or not.  They can be site collections or subsites and do not participate in Office 365 groups.  Classic sites can have modern libraries and pages but they are not truly full modern sites.  Then in modern sites, there are definite differences between the modern Team and Communication sites, the primary being that a Team site provides the glue of an Office 365 group.  A modern Communication site does not, it is just a separate modern site collection.  Modern sites are where Microsoft are putting all their efforts, so I would evaluate those 2 and if you find a reason where a required feature you need isn't available, fall back to classic site then choose.  If ALL you need is a basic list to store some data and all the logic and forms will be elsewhere, you could use an existing site or make a new one for this purpose.  You need to evaluate security requirements to drive this too.  

Either use an existing Modern team site, or create a modern Communication site.  It really doesn't matter.  Either one can hold a basic list of data.  Do you need an Office 365 group?  I don't know, maybe not but these are the decisions you need to match to your requirements.  If the solution is going to be that involved I would make sure there is a specification document as well as a functional specification stating how you're mapping technology to the requirement.