In terms of nesting, if I understand what you mean by that, I use both Airtable (just one account needed) and Softr together, and I have nested 3 levels of records without major issues. The only caveat to that is that I ran into problems when managing visibility show/hide logic options when mixing functionality between different Airtable tables in a single Softr page. It’s not a dealbreaker, but there is scant information that warns users about this issue in my experience (the logic only applies to the top most placed table records). But for straightforward nesting, Softr’s decent, insofar as understanding what you mean about nesting. Eg. In one Airtable Base I have a parent table record, that contains a linked record from another table, that contains a linked record (3) from another table (3 nested records). Softr’s interface handles this. It is for me way more user friendly for non-tech people and also makes it in my opinion far easier to manage user permissions. The biggest reason for going with Softr is the price of adding registered users, which in Airtable is a significant cost.
A downside of intergrating Airtable into Softr is the speed of records showing. It does vary, and sometimes it seems to lag awkwardly but not always. I wish it was consistently snappier than it often is.
I’ve not tried Softr’s own data for backend stuff. I was too committed to Airtable before it became available and I’m reticent to put all my eggs in one basket.
In Airtable’s interface favour, you have immediate changes appear whenever an edit is made, whereas when Airtable records are viewed in Softr the user needs to refresh the page to see the result, unless there is a custom code to make it refresh (which you can do, but still has to refresh the browser). Airtable is also better at logging individual history usage with the records.
Overall for the interface, I really like Softr as you can build out pages, but for data I’m happy with Airtable, except for the display lag occasionally inside Softr (doesn’t impact backend building). For the latter reason, there is a strong reason to place data with Softr.
It would take you a very short amount of time to use the free trial period to see if it can do what you want it to do.