Hi! I want to buy my first professional camera - I just finished my photography class. Which model will be better for me if I want to take portraits: Canon T8i, Canon EOS 80D or Canon SL3? Thanks for your help!
I have no idea which model is best for you. Your exact needs and your budget need to figure that out. Just because a camera is a DSLR does not make it a "professional camera."
If you want a professional grade camera, then you really do not want any of the Canon Rebel series of cameras. While Rebels are great cameras, capable of capturing great images, they lack certain features that professional photographers consider highly desireable. This scratchtes the T8i and SL3 off of your list.
The 80D is a step up from the entry level Rebel Series of consumer cameras. It falls into the mid-range category of DSLRs. Cameras in this category are sometimes referred to as "enthusiast" grade cameras. These include manyof the features desired by professional photographers. The 80D is an older design, which has been superseded by the 90D late last year. Canon cameras in the mid-range category all have models #0D model numbers.
One major difference between midrange cameras and professional grade cameras is the quality of the actual camera body. Professional cameras tend to have a magnesium allow chasseis, instead of a plastic polycarbonate. Professional cameras also have weather sealing against dust and moisture, which DOES NOT mean that they are weather proof.
Canon cameras with #D model numbers fall into the "pro-sumer" or "professional" grade cameras. Most of these cameras are "full frame" cameras, which is something that I hope that they taught you in your class.
If you want to be "serious" about photography, then you will want to start out with at least a midrange camera or a prosumer camera. Current Canon cameras in this category are the APS-C sensor 90D, and the full frame sensor 6D Mark II.
You may also want to look at the used camera market for 5D series of cameras, and even perhaps 1D series, which is the flagship series of cameras in Canon's DSLR camera lineup.
"Canon T8i, Canon EOS 80D or Canon SL3? Thanks for your help!"
The above post is a good start but it leaves a bit unclear. Any of the cameras you mention will take good portraits. Most DSLRs today have a fantastic sensor and supporting electronics with good features. Almost always the only, single, difference is the build quality of the camera and lenses. Yeah, features are added but that really doesn't affect the sensor or the IQ of a given shot. I don't use anywhere near all the ability and features that my 1DX offers. I have made a lifetime out of photography including portrait and weddings, a photo business, etc.
For instance, a 1DX Mk III, Canon's flagship model, costing six thousand+ dollars won't make a correspondingly better picture or portrait than the Rebel T8i does, if any better. But the 1DX Mk III will do it day in and day out day after day for hundreds of thousands of times in almost any condition or circumstance. It is almost if, the 1DX3 can't do it, no camera can, thing. The old sayin', "You can beat someone to death with a 1DX3 and then take the crime scene photos with it." Rebels can't do that!
Most beginners or people just starting out buy a Rebel. If I were you I would buy the T8i but be ready to get into a more professional camera if your new interest grows. Knowing what I do from experience, however, the 90D makes a lot of sense too. The 90D is a very capable camera with an enhanced build over the Rebel line. It just might be all you will ever need.
One thing that is very important, get the newest or latest new camera. You cited cameras that have been replaced by newer models, except the SL3. The Rebel T8i or the 90D are better choices because they will stay relevant longer.
Keep in mind that there are two forms of "professional" photography, and the rules are very different. If you're taking pictures and selling them, as in a gallery, it makes little difference what equipment you use, as long as the result is what you (and the buyer) want. But if you're photographing an event or taking portraits for a client, or any other situation where the original conditions are not reproducible or are reproducible only with difficulty or significant expense, you need really good equipment, including a backup to fall back on if something goes wrong. Those who confuse the two cases do so at their peril.
There was a notable case back in the film era, where a photographer photographed a very important wedding. The laboratory that developed the pictures lost or damaged a significant number of the negatives. After the inevitable lawsuits, the photographer and the laboratory paid to re-stage the wedding, including bringing in guests from all over the world. You do NOT want something like that to ever happen to you.
I can not or do not know a professional wedding photographer that does not have a force majeure clause in the contract. They are idiots if they don't.
PS. A "force majeure" clause is a contract provision that relieves the photographer from performing their contractual obligations when certain circumstances beyond their control arise, making fulfilment impracticable, illegal, or impossible.