What are the best side missions?

Just based on Nexus, Eos, and Havarl:

I found the Kett battle in Eos (their base) kinda fun. Hard but fun as it's just pure action.
Taking down architects was also kinda fun.

In terms of story, I really like the sidequests from the Nexus, too. They don't tend to be very difficult but they're narratively solid and....even thought-provoking, when choices are required.

My favorite side missions so far are on Kadara. You'll see.

I love getting the Arks back

Vaults are fun, too (at least the first few times - sadly there never is any truly special loot (like: That gut/armor-piece (or other piece of technology!) you can only get by going into that specific vault), same when you take down architects (the battles are fun, but they all seem to play out the same (I've only fought 2 of them so far...the first battle was HARD (I met my first of those monsters at lvl 16 and my equipment was not all that decent!))

The game over all is pretty fun - but it could have used more cutscenes (where you chose the dialogue, I hate it when my character mouths off without me having any influence) and some more mechanics like ship upgrades (then again: I think the ship should be armed, even if it's only one puny Mass Effect cannon (that way at least punks like Sloan Kelly aren't a problem - you can threaten to blow them to pieces from orbit!))

greetings LAX
ps: Loyalty missions are fun, too (Loved Drak's mission and Cora's...haven't done any others so far!)