I am not a fan of Savage, but if you are building/modifying it yourself that would probably be the easiest action to start with due to their barrel nut set up. Parts are also fairly common which would make building it out fairly straight forward. Lots of people really like building of Tikka actions as well with great results. I would look at available option from those two first.
There is another thread on here saying that Remington (under new ownership) is starting to ship out actions so rifles, etc will likely become available again. Bergara is more or less a clone of the Remington. As far as aftermarket parts availability, Remington would be king among all, but this is where custom actions do it better.
If looking at the Vanguard/Howa 1500 or Mark V I would just buy the complete rifle that you want instead of trying to build or modify one.
For reference, the Bighorn/Zermatt Origin actions are about $875. If in your search you start finding actions prices reaching near that point I would still suggest going with a custom.
Hope this helps.