SLR is most boring and not created by imperfection and accident film gear photography I ever seen.
If you have normal Canon DSLR or at least EF lenses, get EOS 300 and use exactly same lenses. With all of those old SLRs you will waste more money, but results are going to be exactly the same. Something sharp, something in bokeh. Meh...
Diana Mini is another side extreme. Lens is garbage and camera is even more.
I recommend classic camera which started Lomography. Spend sometime to find what camera is this. BBC made amazing documentary about it. Worth to watch if you would like to find out what creativity is with LOMO.
But if you want it on cheaper side, I recommend any regular P&S with focus fixed lens. They seems to be more robust than plastic lomography cameras are, but results are very close in inperfection. I have fixed focus, one speed, one aperture P&S, purchased for five. It never limited me, it has built in flash and waterproof case. And I used it more in 2017 than Canon and Nikon SLRs. I used it with C-41 and results were funky enough and I used it with bw film and flash, made prints and they are not typical SLRish photography.