Wordwall.net provides a large number of easy-to-create learning activities, including:
matching games (memory match, speed match, and drag-and-drop match)
sorting games (speed sorting and drag-and-drop sorting)
anagrams, crossword puzzles, scrambled sentences
diagram labeling
gap-fill
random generators (cards, wheel)
flash cards
some arcade-style games (such as Whack-a-mole)
Many (but not all) of the activities allow you to add your images; some allow you to add your own sound or to use a machine-generated voice. Some activities are only available at the higher of two paid membership levels.
A nice feature of Wordwall is that by creating one activity (such as a matching pairs activity), you can instantly generate other activities of the same type (such as speed match, quiz, and drag-and-drop match) using the same data.
Here are links to screencast videos showing how to create many of the activity types:
With an account you can also access and use many pre-made games by other members. However, you have to review them carefully for errors and to make sure that they include content that your learners have already learned.
Wordwall games can be used in class or assigned for individual use. They can be assigned for anonymous use (with a single link that all learners can use). You can also assign them as "Enter Name", meaning that a student needs to enter a name (any name), and the results will be reported back to you. No individual student account or passwords are needed.
Pros:
Very easy to create activities, easy to add images and audio
Nice variety of activity types to practice a wide range of skills
You can get reports of leaners' use if you assign them as "Enter Name"
You can vary the difficulty level, add time limits, limit the number of wrong answers, and adjust the speed of some activities.
Cons:
The free account is very limited (5 activities), so you'll need a paid account to get much use. The Standard membership is $6/month (which can be cancelled at any time) or $64.80 if you prepay for a year. This level includes 18 interactive activities. The Pro level is $9/month or $97.20 if you prepay for a year; this level includes 36 interactive activities.
Not all activities allow you to add images or audio.
The "hangman" spelling game doesn't offer nonviolent alternatives (like Flippity does).
Although the templates are very easy to use, you can't modify them. I find that some of the matching activities are hard to see on phone screens.
If I had to choose between Boom Cards and Wordwall, I would chose Boom Cards for the flexibility that they offer and the lower annual cost. With this flexibility comes a higher (but not too high) learning curve. If ease of creation is more important than flexibility, then Wordwall is the better investment.