Hi,
I will try my best here:
MIXXX is 100% free opensource. It has a healthy community and lots of support.
It may or may not have the controller you use, if you use one. But, no worries the community most likely has people that have mapped the MIDI for you.
Tractor 3.0 I think offers a free version. It may not see controllers in that mode at all. I have not tried it.
The software I use is Virtual DJ Pro since version 5.
Virtual DJ has grown up a ton since version 5. Also, I will let you in on a cool little thing it does I am not sure others do.
If you use a controller or are going to get one, VDJ FREE will see it for 10 minutes. This sounds unimpressive, until you restart it. 10 more minutes. While it is awkward, you get into a rhythm. And, this allows you to save up to buy the paid version. As you use the software for free. Free has full access to settings, and feel of how it works. You can't stream from VDJ but, OBS, XSPLIT work around that fine.
No software or hardware make the DJ better. That is up to the DJ and how they use the tools. Some work better for others, but that doesn't make it the best option for everyone.
Don't worry what others say if you use MIXXX or anything else that isn't Serato. I am not sure RekordBox sorry for spelling may offer a free option.
Try them all even if trial is the option. Because you might find you hate some software, and if you only try one or two option you could miss out.
Good luck,
Wheelchair Beats on BandLab