The tortoise diff tool when doing most stuff.

Winmerge if I am manually comparing directories (it can do images/pdfs too!)

I use GitLab diffs in single-file-view mode, TortoiseGit Merge when it exceeds what GitLab can reasonably display (including block indent changes I can ignore in TortoiseGit Merge or moves I can better track), and WinMerge (previously I used KDiff) for manual copy-paste text diffing (like copying blocks from the code change diff to compare similar, categorically similar code, or code moves, etc)

For comparing and selectively applying changes in many files, WinMerge is my tool of choice. But for resolving merge conflicts, I go with Tortise Git.

Kdiff3

My favourite is Meld

Not a diff, but a merge tool.

https://mergiraf.org/introduction.html

I’ve been using delta for a while, alongside lazygit, and enjoying it.

alias diff='diff --width=$COLUMNS --suppress-common-lines --side-by-side --color=always'

I like kdiff3, vimdiff, and … intellij. Kdiff3 and intellij do “directories / file structures” too but I’m not sure the level you want it. Neither are cli though.

I use emacs’s magit for git stuff (the bulk of things) and emacs’s ediff for most other things.

Good if you know emacs, but hard to recommend using it for someone who doesn’t.

EDIT: Oh, one exotic utility that’s useful for some rare cases, not really for interactive merging of code — wdiff for word-level diffing. Most code can reasonably be diffed on a line-by-line basis, but that’s not true for some text formats, which can have very long lines. Human, natural language in text format, is one good example.

I’ve been using SmartGit for about a decade now. While I don’t typically need a git GUI, I do appreciate it’s diff’ing and 3-way merge.

It’s free for open source use and they do have a lifetime license option to avoid the subscription for commercial use.

I’m mainly interested in making code reviews a little easier to manage.

One thing I haven’t seen mentioned yet, here: All future diffs become much easier to read if the team agrees to use a very strict lint tool.

I know, I know. “Code changes should be small.” I’ve already voiced that to my team, yet here we are.

I understand from another Lemmy thread that the tradition is to toss the offending team members’ laptop into the nearest large body of water.

I like the merge and diff tool integrated in the various Jetbrain IDEs.

Gnu diff for the basics or if I want something automating diffs, beyond compare or winmerge if I’m stuck with windows for gui tools.

Probably won’t solve all of your problems, but I like to at least change git’s default pager to delta.