I have fallen in love with fish shell's abbreviation approach for aliasing.
The main reason is simply illustrated like this:

Most of the time I would run ls command with ls -la options.
So I alias it to simply l => l = ls -la.

Now with nu 0.25.x approach to alias, in some cases where I want to run ls -lad instead, I can still invoke it with l -d.
However, in the super rare cases where I want to run ls -l (without -a), I cannot use l at all.

With fish shell abbreviation approach, when I type l<space> , the command is replaced with ls -la<space>, so I can conveniently edit the command with both additions and deletions.

Of course the example above does not make sense in practice, because it would be faster to simply type ls -l instead of l<space><backspace><backspace>.
However, please imagine a very very long alias where sometimes it makes sense to edit a tiny bit in the middle of the command, not at the end.