Reads a bit like an ad for some popular products. Most equipment junkies agree that SelectTech dumbbells are the worst choice. Cheap spinlocks are better because they're sturdier, can take some abuse. Regular handles are 14" and you can get 18" handles. With Bowflex and their copycats, the dumbbells are an annoying length at any weight.
Ironmasters are the best dumbbells you can quickly adjust, followed by Powerblocks. They get shorter with less weight. Quick adjustment is not very important once your weights get above 50 lbs because you're taking long enough breaks to switch weights and get bored.
Not only that, but unless you get a few optimal weights, they are unbalanced, so you are limited by what you can do. Sure, some things it doesn't matter if the right side of the weight is the same weight as the left side, but when I tried it I couldn't get past this.
Ironmasters are the best dumbbells you can quickly adjust, followed by Powerblocks. They get shorter with less weight. Quick adjustment is not very important once your weights get above 50 lbs because you're taking long enough breaks to switch weights and get bored.