Dumbbells are the cornerstone of any good home gym. They allow you to train your whole body and they are relatively inexpensive compared to high-end gym equipment and machines.
In the beginning, all you need is a pair of light, medium, and heavy dumbbells based on your relative strength levels. I recommend a pair of 10, 25, and 50-pound dumbbells as a good starting point for most men and advanced trainees . Women and beginners can cut those loads in half if needed.
But adjustable dumbbells are a great way to access a wider variety of weight selections in 2.5-5 pound increments while taking up a very small footprint in your home gym. I’d definitely recommend this for a longer-term investment or if you have more funds at your disposal.
As the dumbbells get heavier, they do get really big and cumbersome. I’ve noticed that the same weight “feels” 5-10% more challenging in the heavier loads due to the balancing act of the larger bells. But if anything you could say that allows a lighter load to go a longer way (though it can hurt your ego).
Please note that Powerblock is the only brand of adjustable dumbbells that I’ve personally used so I can’t speak to the quality of the other brands. But I dig them and I religiously use the pair that goes from 5 all the way up to 125-pounds. The elevated weight stand is also great for storage and easy loading adjustments.