Depends on the job it’s needed for. The 660 is total junk if you need a limbing saw you can swing all day. 261 is going to disappoint if you need to buck big wood. There is no best. Only what’s best for your needs for a given job
Been living in the real World- those wee saws might suit you and your conditions- but would possibly be at their max in East Coast hardwood of decent diameter, be mediocre where I live and next to useless in Australia cutting dead standing hardwood species there- yet maybe handle West Coast softwoods a piece of weeze.
Like jasent says above- there is no one perfect best for all situations, only what's best for your needs for a given job.
The op's original question has been accurately answered , you should learn to read a little better brother . He lives in Pennsyvania , not Translyvania or Tasmania mate ! The best Stihl saws capable to run a 25 " bar efficiently , remain the MS400 for limbing & moderate felling & bucking at 66 c.c. It is almost as lite as many 50 c.c Class.saws . Both the MS461 & MS462 at 76 c.c. + are strong middle weight saws that will pull a 25" bar with authority . So again , his question as stated has been accurately answered ...I live in the Real World were the Big Dawgs Eat ...Eh ! 3120 XP or 592 XP rule production felling ....880 are milling saws brother & old school technology & neither routinely wear wimpy 25 " bars !