My yard is... maybe 1,000 sqft and I use a Scotts 14" reel mower and a Black & Decker 40v Battery electric weed eater.
Having a tree isn't bad, I use the weed eater around the base BUT! Mulch is a killer.
I have the wood kind of mulch and it 100% just stops the blades. Full momentum to dead stop. So, I find myself picking up most big chunks of wood before mowing HOPING I don't get caught up.
But honestly, it is really easy! Plus, it's quiet, green (if you're into that), and basically self fertilizes.
I'd recommend a reel mower and electric weed eater for a small yard.
However, don't by a 14"... get at least an 18" reel. My 14" works fine but I do wish it was a little wider. (No that's what she said)
And for the weed eater, the battery lasts forever! I bought a B&D combo kit with a trimmer and blower, I use both and still have at least 25% battery left.