Every garden, every gardener and every job is slightly different and what works for one might be useless for another. But there are a few basics:
Regular or EN Pro: the heavy duty EN rated ladders are designed for landscapers, tree surgeons and other tough jobs - but do perfectly well in private gardens. If the ladders are used day in, day out, or will be taking a heavy weight of more than 100kg, think about the EN Pro. For regular use, the regular Niwaki Tripod Ladder will do you fine.
Size: using our SSH (Safe Standing Height) combined with your own height, and the height of the job in hand, we can fairly accurately say what size ladder you need (for a specific job). On the larger ladders (8' and up) the SSH is 3 steps from the top, so the top is effectively your handrail or something to lean against. On the 6' model, because it's smaller, the SSH is officially 2 steps from the top, but for more cautious users we still recommend 3. So, using the 8 footer as an example, you can stand, comfortably and safely, at 5'. Let's say you're 6' tall, which means the top of your head is at 11' and you can reach to about 12', arm outstretched. For hedge pruning, where ideally you want to be working between waist and chest height, you'll have a working height of 8-10'. Of course it's higher if you're taller than 6', and lower if shorter.
Weight: they're all remarkably light, and folded up into a lump of aluminium, in a suitcase, would seem like nothing at all. What they are, though, is tall, and wide. Moving them around, especially when you're deep in the undergrowth and you need to move a few feet, can be tricky: the legs stick out wider than you think, and the taller ladders can be top heavy. Taller people tend to hold the ladder higher up, so this is less of a problem - for shorter people it can be a real bore.