361 up in the Tree
I have climbed for 15+ years now in my own company and have used 026, 361, 044, 064 and 660 up in the trees when the need for it called.
MS361 is your best bet up in the tree if you need to cut big chunks or top a large diameter tree. It is light and can handle a 28" Bar if needed. If you only need a 20" Bar and want to stay as light as possible then go with a HUSQVARNA 353 or a DOLMAR PS5100. The DOLMAR is a little heavier then the 353 but also has more power.
STIHL 020AV, 020T, MS200T, 026, MS361, 044, MS440, 064, MS660
HUSQVARNA 350, 254XP, 262XP, 372XP, 575XP, 394XP, 3120XP
MAKITA 6401, 7901
EFCO 165