I am now pretty much exclusively running TRS19 and once I've finished making my own route and asset transfers from earlier versions I'll be archiving them away and not using them anymore. That said I will also say that there are things I don't like in TRS19 and there are things that I do, - it's just that on balance I consider the good to outweigh the less than best.
Some folk like the UDS, I don't as I find it too confusing to use and it's too easy to lose any work you've done due not saving in the right place at the right time according to some non intuitive esoteric formula. I strongly dislike the popup message boxes that warn against connecting incompatible splines since they always seem to popup whether I was doing that or not and cancel whatever it was I was doing. To get past them I now have to employ workarounds that I've never had to do before in other versions. The charcoal grey letters on a black background in menus might be very modern and cutting edge, but it's terrible for anyone who has eyesight problems as I do due to having narcolepsy. Hiding tool options in menus instead of having them on the toolbar has been done to death before, but I'll still mention it. And then there's the environmental lighting which no matter how carefully it's adjusted will never completely lose the supernova effect from at least one direction. There's a few recent fun bugs too, but apparently they are going to be fixed in the next patch/update all going well.
On the good side TRS19 mostly does what it says on the tin and runs faster and more smoothly than TANE and doesn't crash. Surveyor runs smoothly as well and doesn't pause, glitch or hang up. TRS19 is the future and for all its faults it is where Trainz is going and the older versions are going to get increasingly left behind unfortunately. My general purpose Trainz computer has a very average spec and is nothing startling which makes it a good test bench. I own a much more powerful computer as well which can run TRS19 with everything on ultra, but where's the fun in that? - and besides if I'm doing content creation it's best to do it on an average machine rather than something that can crunch through anything without a flicker.
So really in the end you pay your money and you take your choice. TRS19 isn't perfect and most probably will never be perfect, - then no software ever is.