Ironmaster Dumbbells, Kettlebells
Dumbbells are extremely versatile: they offer huge exercise variety, and because they're used by each arm independently, they help repair of strength imbalances where barbells don't, and the arms-independent aspect means your core is automatically worked more than with barbells.
And...dumbbells don't go out of date too easily! But...
These dumbbells are the best to train with. And they can convert instantly to a kettlebell set. They're super compact.
Replace a wall of regular dumbbells with these adjustables in a space 2 foot square. 34 kg sets (5 to 75 lb) come with a stand with inbuilt storage. And you can upgrade from the 34 kg (75 lb) to the 54 kg (120 lb) set for the difference in price. (And further, to 72 kg sets; people do this!)
They cost hundreds less than the equivalent in hex dumbbells, and they're nicer to use because they're much more compact. There's little overhead clash with heavy weights during presses, because they're not bulky, for instance, and they're more maneuverable. And they're more of a reliable pleasure to use than common plastic-dial-driven-and-breakable adjustable dumbbells. Best of all, there's no clutter.
Ironmaster kettlebells use the same US-patented, instantly-dependable locking principle. Finally, adjusting from one weight to another happens in smaller increments (than with other dumbbells and kettlebell standards), so with both kettlebells and dumbbells you get stronger faster and more smoothly. Less injury risk as well.