What free PM tools would you recommend?

I do get your point about Excel not being a good fit for project management (the company I work for uses google spreadsheets to much the same effect).

But you are missing one key piece--everyone either knows how to use a spreadsheet or can learn quickly. Therefore, it is the lowest common denominator--a new employee can be up to speed on using Excel as a project management tool very quickly. That is in contrast to most of the specialized tools, which have lockin and training costs.

I really like Asana. Though even that has one shortcoming in that task dependencies is clunky.

Trello is something that I use personally so I can't comment on its effectiveness in a group environment.