Portable easel is a broad term covering several quite different objects, and buying the wrong kind is the usual reason one ends up in a closet. This covers what each type is for, what to check, and the honest case for not buying one.
The five types

Tabletop A-frame
A small folding wooden or aluminum frame that stands on a table and holds a canvas upright at a slight angle. The cheapest and most common.
For: small and medium canvases, working at a dining table, and small rooms. Also doubles as a display stand for the finished painting.
Against: it takes the table space the canvas would have taken anyway, and it will not hold anything large. Most top out around twenty to thirty inches of canvas height.
Field or sketching easel
A lightweight tripod with an adjustable mast and two clamps. Aluminum ones fold to about the size of an umbrella and weigh very little; wooden ones are heavier and steadier.
For: painting outdoors and anywhere you need to stand. The obvious choice if you want to work in a park.
Against: light aluminum ones are unstable in any wind, and they carry no supplies, so you need a separate bag.
French easel
A wooden box with folding tripod legs and a drawer, which closes into something like a briefcase with the canvas strapped to the outside. Everything in one object.
For: anyone who wants to carry the whole setup in one hand. The drawer holds paints, brushes and a palette.
Against: weight. These run somewhere between twelve and twenty pounds loaded, which is fine from the car to a bench and unpleasant on a long walk. They also take practice to set up.
Pochade box
A small shallow box that clamps onto a standard camera tripod. The lid holds the panel, the base holds a palette and a little paint.
For: the lightest genuinely usable outdoor setup, and the modern answer for painting away from home.
Against: small panels only, and you need a tripod sturdy enough to hold it, which is a second purchase.
Studio H-frame
Included so you can rule it out. A large, heavy, wheeled or fixed easel that is stable, adjustable and excellent to work at. It is not portable in any sense and should not appear on a list like this one, however often it does.
What to check before buying
The maximum canvas height. The first spec to look up and the easiest to get wrong. Buy for the largest canvas you realistically paint, not the largest you imagine painting.
Weight, honestly assessed. There is a real trade-off here: heavier means steadier, lighter means you will actually take it out. Be truthful with yourself about how far you will carry it. The steadiest easel in the world is useless in a cupboard.
A hook or a way to add weight. Any easel used outdoors needs a way to be anchored, and the standard solution is a hook under the center from which you hang your bag or a bag of stones. Wind is the main cause of ruined outdoor paintings, and this costs nothing.
Whether it tilts forward. More important than it sounds. Tilting the top of the canvas toward you kills the glare from overhead light on wet paint, which is otherwise maddening. And if you ever work in watercolor or pastel you need a shallow or flat angle, so an easel that only holds a canvas near-vertical will not do.
Height adjustment for sitting. Many people paint sitting down, and a lot of easels are designed around standing. Check the mast drops far enough that the middle of the canvas is at your eye level in a chair.
The feet. Rubber, non-slip and, for outdoor use, ideally pointed enough to bite into soft ground.
How it folds. Read a few owner reviews specifically about assembly. Instructions on this class of product are often poor, and an easel that takes fifteen minutes of fiddling to set up is one you will stop taking with you.
Wood or aluminum
Beech and oak are heavier, steadier, and pleasanter to handle. Aluminum is lighter, cheaper, packs smaller and does not mind rain.
If it is going outdoors on foot, take aluminum and plan to weight it. If it lives at home and travels occasionally by car, take wood.
When you do not need one
Worth saying, since most articles on this subject open by insisting an easel is essential. It is not.
An easel is genuinely useful when you need to step back frequently and judge a whole composition, which mostly means free-hand painting and larger work. It is much less useful for close, detailed work, where you are leaning in anyway.
For a numbered canvas in particular, a flat or gently sloped table is often better than an easel. You are working close, filling small printed regions, and you want to rest the side of your hand somewhere steady. A canvas standing upright gives you nothing to brace against and encourages you to hold the brush at arm's length, which is the least controlled way to paint a fine edge.
If you do want the canvas raised, a small tabletop easel or even a stack of books under the far edge gets you most of the benefit.
What comes with our kits
Our framed sizes, the 12 by 16 and the 16 by 20, include a wooden tabletop easel, which is enough for a canvas of that size and folds flat afterward. The unframed option does not include one, and we would rather say that plainly than have it turn up as a surprise.
You can paint any of them perfectly well without an easel. Tape the canvas to a board, work on a table under a lamp positioned so your hand does not shadow the section you are painting, and that is genuinely all the setup required.
The range is in our collection, and we can print one from your own photograph. If you are setting up for the first time, the beginner guide covers the rest.