Paul, for 1 acre you could easily go with a nice garden tractor or step up to a Sub-Compact Utility Tractor (also called a Sub-CUT). A premium garden tractor will cost much less, but the Sub-CUTs offer more usability. Your budget may determine the choice.
Looking at the better garden tractors (GT), skip shopping the "big box" store completely and seek out a Cub Cadet, John Deere or Kubota dealership in your area. All 3 brands make some very nice Garden Tractors, the Cub 3000 series machines, JD 300, 400 & even 500 series machines would suit you, as well as the Kubota GR or G series garden tractors. Any well made premium brand GT will last you for 15-20 years without much trouble, they are excellent at mowing the lawn and will accept front mount snowblower, front blades, pull wagons, and some will till the garden; they will all have HST standard.
Stepping up you could look at the Sub-CUT class of tractors. Cub Cadet 5000 series, CASE/Farmall DX"e" series, Deere 2210, Kubota BX series, Massey GC, and New Holland "TZ" series tractors make up the known sub-comact choices available. A Sub-CUT is going to give you a much heavier frame than a GT, it will give you hydrostatic transmissions, rear PTOs just in case you want to till a garden some day, a mid-PTO for your mower deck and hydraulics to control things like a front end loader, or to lift a front mount snow blower (which will be powered by the mid-PTO). But honestly the Sub-CUT machines are on the large size for 1 acre.
I would stay away from anything larger than the above machines for 1 acre, it is simply overkill and probably only justified if you have testosterone envy. The small frame CUTs already mentioned (JD 4110 and Kioti CK20) are nice machines, but they are going to be taller and, especially in the case of the CK20, much heavier on your lawn. These may be nice tractors, but there is no reason for them on 1 acre; they don't turn as tight as smaller machines, making it harder to mow around plantings, the taller roll bars don't fit under small ornamental trees either. GTs are very soft on the lawn, Sub-CUTs are also, but a small frame CUT will give you weight you may not want on your lawn. I'm just not one who believe in buying a bigger tractor than you need, I find they often end up making more work in your yard as you will have more to push mow or weed wack because you can't get into places that a garden tractor, or perhaps a Sub-CUT will get into.