While I took down half a dozen 25 foot sycamores with a Wickes bow saw, and wouldn't have seen a need for anything else.
Got a palm in the corner of the garden that really ought to come down as it's only a couple of feet from the neighbour's house, and I'm not convinced hand tools are wrong for that even though the trunk's about 18 inches across - but I'm not convinced I'm the right person to do it.
Like Charlotte, I'd really fancy a chainsaw - but I know damn well it would be for shits and giggles rather than anything else, and I'd start with a decent course.