1.5 Mowing Acres will be best with a 54" mower or larger. You can go smaller, but why? Budget is the factor. 1.5 acres on a 54" is about an hour or less. A Cub Cadet Ultima 54" ZT1 with a Kohler motor will get you a decent mower with a Fabricated deck and easy maintenance and wide parts availability. Prices are under 3.5K. You will be putting less than 50 hours a year on it so longevity is not an issue. Blow it off every time, wash it occasionally, service it IAW the manual, slap some Gator Blades on it and always store it inside. Its a residential application so don't get wrapped up in the comparisons too much. Its a very low use system and any of them will serve you well for the short amount of mow time. If you were using it daily I would have different advice. I take care of about 7 acres each week of the season where the bigger commercial mowers make a difference, but that is not your profile.