IMO the Message module could be a perfect alternative, for situations where "syslog" cannot be used. Using this module, you can create your own custom "Events logging" (to register things that happened in a site). Specific to this question here, I'd create a so called "Message type" that contains the actual data to be logged.
You could even track things like updates to nodes, i.e. how data looked like before and after they got updated, a kind of "light" revisioning (only for those node attributes you want to know about).
About Message types: think of them as equivalent to Content types, whereas you create messages (instead of nodes) of a specific Message type (instead of Content type).
A really interesting facility of the Message module is its perfect integration with the Rules module. Have a look at the answer to "How to implement a follow author (or user) function?" for way more details on that.
As an example, here is a (rather basic) custom rule:
- a Rules Event like "Before saving a new node", of "After updating an existing node" (or variations of these events).
- a Rules Action to "Create a message" (of a selected Message type).
That's really it ...
Example included in Commerce Kickstart
A great sample of this can be found in Commerce Kickstart, which uses the Commerce Message module, to create such "Events logging". In that case in the format of an Order History, as shown in this screenprint (from this module's project page).
Replicate/replace the Activity module
Should you want to do so, it seems perfectly possible to build a view (report) that contains the data similar to what you can do with the Activity module as shown in this screenprint (from this module's project page).
More info about the Message module
The Message module is an amazing module, it is fully entity based, which implies that it perfectly (out of the box) integrates with modules such as Views and Rules.
Though there is not a lot of documentation about it (which is what makes it a hidden D7 gem ...). A possible way to get started with it, and to get an idea of the kind of things it can be used for, is to have a look at the answers to: