In TS12, alot of old assets do not work ... unless you apply alot of fix's to the config files.
In TS10 alot of people purposely never update patchs beyond build 44088, because of losing compatability mode, if you patch beyond that build.
If one were to buy TS14 (which is not built yet) it might have better graphics than TS12 ... and hopefully not have a whole new barrage of glitchs and bugs.
I use TRS2006 to build routes, as it is easier to use (user freindly).
I bought TRS2004 because I found it on E-Bay for cheap.
I bought TS10 because it has compatability mode (as TS12 does not), and because I had a discount voucher. Sadly TS09, 10, 12 do not run with good framerates on low end PC's.
I dint' buy TS09 because it is a rushed released predecessor to TS10, an has no advantages over TS10.
Once people buy a $1500 PC they never use 04, 06, 09, 10 again ... and stick with TS12.
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Does TS12 run great on your PC ? ... If so ... Stick with it.
When TS13/14 comes out you can rush right out like all the rest of the folks and buy it ... convert all your TS12 assets to the higher version ... and trash TS12. (but this may be a long, long, time from now, if ever).