Stihl 044, 441, or what ever new # they have for that size saw.
Been using the 038,041,& 044 for 26 years- Saws were designed to work all day.....YOU WILL NOT BE DISAPPOINTED. Also, if you do enter in to the world of proper tree care & removals, the 044 will be much desired for blocking trunks & removing large limbs while climbing.
I wouldn't go any larger, we have larger saws and they get used few times throughout the year. 24"with skip tooth will cut 98% of the trees encountered if you are experienced. That being said, "big wood" beings about another set of mental issues, better have clear communication & make sure your guys are quick learners - professional leaf rakers and grass cutters can easily find themselves outgunned & hurt. A bigger saw normally doesn't make the job go easier, if anything Without proper experience, it will add to the days frustration & expense.