It would work great with Entangle or Web, they need an action to get out of, and the enemy is denied exactly that, but these spells require concentration too.
You answered your own question; Stinking Cloud is a great spell to use against creatures which have no movement. Yes, you're right that web and entangle would pair well with the spell, and also that those spells are also concentration. This means that you'd generally want to restrain the creature(s) in other ways, such as having an ally cast a spell. If you don't have spellcasting allies though, don't despair. There are other ways of restraining creatures.
Grappling (PHB 195) is an action that any creature can take, which is part of the "Attack" action; if you make multiple attacks, a grapple attempt can replace as many of them as you like, up to your total number of attacks. It's an opposed athletics vs acrobatics or athletics check, so with two attacks, you'll have a pretty good chance of grappling someone. Grapple reduces a creature's speed to zero. It's also an action to attempt to escape.
While most spellcasters won't be very effectual at grappling, with certain exceptions, many of your strength based allies will be great at this, so feel free to wait until someone's grappled and then set a stinking cloud just out of range of your ally while covering the grappled creatures.
This is very useful against enemy spellcasters especially, as well as being good against other creatures. Since the cloud obscures vision, it prohibits spellcasters from using many of the bonus action spells they would otherwise be able to make that require sight. This includes the only bonus action teleporation spell, Misty Step.
In a situation where you expect combat, it's possible to set traps against enemies so as to limit their movement. Consider setting caltrops, ball bearings, and hunting traps. If they can be obscured, then you'll be well able to set up a decisive ambush. In other situations, the Stinking Cloud itself might obscure traps that creatures, in seeking to escape, may bumble into.
As mentioned below, it is possible to attack a creature within a heavily obscured area, and usually without disadvantage; even though the attacker is hindered by the lack of sight, so is the defender.
Advantage and Disadvantage
It should be noted that against creatures inside the Stinking Cloud, attacks have both advantage and disadvantage; heavily obscured areas result in the blinded condition, which would affect both the attacker and defender for the purposes of attacking a creature in the cloud. This would even out. A creature attacking from within the cloud at someone outside of it would suffer disadvantage however, so you're never at a tactical disadvantage.
While Stinking Cloud comes with limitations, those limitations can be effectively circumvented by party cooperation or preparation. It's only as useful a spell as you make it, so if you want an advantage, don't just rely on spellpower, but engage in cunning actions.