I understand your desire for a canister and grease-able spindles but at 3 acres of easy cutting, you may be throwing lots of moeney and perhaps over buying. I had 2 acres of lawn to cut which led to four acres. I had an old White, 18hp 42"deck which would take me the better part of the weekend to cut, every weekend. I was spending every second of down time taking care of the lawn. Don't get me wrong - I love taking care of it but EVERY weekend and ALL weekend?
Point is, I think we were in the same boat. I started looking at zero turns and wanted one due to the power, speed, and the ability to get very good quality (commercial grade.) Problem was I didn't want a 1-trick pony. I needed something that would cut fast but still pull an aerator, broadcast spreader, garden cart.
Where I ended was with a Craftsman PGT9000 - for these reasons. Close (kinda) to a zero turn. It's 50% faster, 50% more power and 25% more cutting, (54"deck) than what I had. The other big reason is Sears Essentials was going out of business and I got the tractor and a triple bagger for $2864. I will NOT dispute what the reviews state about this tractor because by and large, they're all true but for 3 acres of manicured lawn for your purposes please consider higher end garden tractors. As you stated, garage space is a concern. Me, I'd love to have the PGT9000 for the fields and a zero turn for the manicured lawns but as you said, I wouldn't be able to store that many goodies either.
I will also share that this PGT is as fast as some zero turns, (I've seen ranges from 7 - 12mph.) This PGT does 7.6mph and it flies through the cutting. It literally more than halfed my time. I'm not trying to sell you on mine because I think there's better, but more suggesting you look at garden (vs lawn) tractors more before ruling them out. I thinks you'll get more versatility.
Just my opinions here meaning to help. Either way, you seem to be doing good research. Look forward to hearing what you decide on.
RickO