I would seriously take a look at the sub-compact class of tractors. The Massey GC, the Kubota BX, the New Holland TZ and Deere's sub compact are the 4 sub-compacts that come to mind. For 3 acres they will give you plenty of capacity to do what you describe without taking too much garage space and all are great for mowing.
And if this is your first tractor the I would suggest you only look at models that have HST transmissions. All the above sub-compact tractors I mentioned are HST units. If you go up to a compact, you will give up some manuverability which will increase the time you spend mowing, but it will give you greater ground clearance if you plan on using a Front End Loader. In any case, I'd definately stick with a tractor that has HST if you move up to the compact class. Kubota, New Holland, Deere, Massey & Kioti all come to mind as compact tractors with HST.
I'd also look for something about 21 to 24 hp, with mid & rear ptos.