Browse Nexusmods to find what you're looking for.

Cosmetic mods are always fun to mess around with. There are too many to recommend here, but having more customization options is always great. Ditto for clothing and armor mods.

Some relatively unbiased mods that I like:

• LE1 Community Patch - fixes a bunch of bugs and continuity issues in LE1.
• Pinnacle Station DLC - restores the lost ME1 DLC, which isn't included in Legendary Edition.
• Alliance Uniform Consistency - backports the LE3 Alliance outfits to LE1 to create better continuity.
• LE3 Community Patch - basically fixes a bunch of bugs and continuity issues in LE3. This mod also comes with a modding framework, so several other LE3 mods require this one in order to function.
• Expanded Galaxy Mod - adds a bunch of features, including QoL upgrades, a handful of cut content restorations, and some fun customization options on the Normandy.
• Immersive Emails - Adds the "text message" system from the defunct Datapad app to LE3. Basically, characters will send you messages every so often based on your actions. What's really cool is that companions will send you messages reacting specifically to whatever mission you just took them on, and most of the romance options get unique versions as well.
• Optional Flirting Mod (LE2 and LE3) - gives you more control over what romances you want to pursue, and lets you choose between flirty and non-flirty dialogue options. Doesn't change the story beyond altering what dialogue options contribute to romances.

There are other character and content mods that I love as well (eg, Happy Ending Mod), but those start to veer into canon-altering territory so I'd recommend deciding on those for yourself.