what is the best DSLR cameras for beginners?

Canon EOS Rebel SL3 / EOS 250D.

There is no "best" DSLR.  Each has its own pros and cons.  If you search for best, you'll never wind up choosing.

If you are using only for photography and not video....really any Brand name DSLR made in the last 10 years should be fine.  Just pair it with a good quality lens.

sony brand is the best

Canon EOS Rebel T100 is the best DSLR camera for beginners.

The one in your hands.

I like Pentax, and recommend the K-70, but there are no bad DSLRs.  Some people prefer Mirrorless (like the Sony models mentioned) for their smaller size and lighter weight, but I've never been impressed with them.

You're the one who'll be making the mistakes as you learn to get the best out of it, so it's your choice.

sony nex 5n or sony nex 5

Mid-range Canon 80D/90D.  You get a much better viewfinder and sensible physical controls for the various functions. The last thing a beginner wants to be doing is fiddling around in the menu while the photo opportunity vanishes.

Short answer:  There are no bad DSLRs.  Buy a cheap one just in case you lose interest in photography.  Instead of the DSLR, consider the mirrorless camera since the industry is moving away from the DSLR.  By the end of this decade, it's likely that there won't be any DSLR on the market.  Considering that the lens mounts are unique, and you'd need lens adapters to use any DSLR lens on any mirrorless, and the fact that when one does this AF performance drops, I would recommend looking at a mirrorless instead of a DSLR.

Cameras are tools, and as such they're all designed for different tasks.  Imagine I asked what's the best hammer.  If you knew anything about hammers, you'd know that there are many different types.  There are framing hammers, roofing hammers, sledgehammers, etc...

Generally speaking, the average beginner will photograph the same types of things: their family/friends, things they're doing, places they've been.  What they're not typically doing are sports, wildlife, underwater photos, to name a few.

With this in mind, any DSLR is likely to be vastly more than good enough for the needs and expectations of any beginner.  To be sure, you need to determine what types of photos you want to make.  Once you've done that, then come back and ask your question amended with these types of photos.  Then, and only then, can anyone recommend a DSLR that will meet your needs and expectations.

With that said, if you're dead set on getting a DSLR, take a look at Canon's T series.  If you know that sports/fast action is what you want to do, then go with something like an 80D, 90D or a used 7D.   I'm not a fan of Nikon's D3xxx series of cameras because they don't have an internal AF motor which makes buying and using many Nikon lenses problematic since not all lenses have AF motors.  In other words, many lenses that you may want would be manual focus if you got a D3xxx series of Nikon.  If you're going to go Nikon, look at their D5xxx or D7xxx if you know that sports and fast action is what you want to do.

If you want to get into photography but no aspirations to be a major enthusiast or pro, then Pentax makes some of the best DSLRs on the planet.  Their KP or K-70 are excellent.  But if you know that sports/fast action is what you want to do, stick with a Canon or Nikon instead.  Any other type, and Pentax has a major advantage over C/N for the non professional.

Shop at places such as bhphotovideo.com or adorama.com.  They're both real brick-and-mortar camera shops that you can call and get advice.  Their sites are purpose built for camera gear.  Avoid amazon like the plague.

The most expensive they can afford.

There is no best dSLR for beginners. If the beginner can afford to learn photography with a full-frame dSLR then so be it. Anyone who opposes the idea is simply jealous.

The worst dSLR for beginners is also the worst for everyone else and those are the bottom-of-the barrel models, the so-called entry-level dSLRs. These are the cheapest and hardest to use even if you already know what you're doing. This is why you must buy the best you can or at least a mid-level model. The more expensive the dSLR is, the more relevant the features are for serious photography and the higher the chances will be for you to enjoy shooting pictures with it.

There is no such thing as a "beginner" camera.  

You have to learn how to use any camera correctly, 

largely by reading and re-reading the Owner's Manual 

many, many times and doing as it says.                 

Taking a class is also a very good idea, 

as is reading articles on various aspects of photography.     

That said, Pentax offers very good value in sensibly designed 

and (relatively) easily operated DSLRs.