Sunstar 1:18 BTTF DeLoreans have a good built quality to them as it's die cast metal with stainless steel.
The DST and Welly BTTF DeLoreans are made of plastic. The DST model of course is larger with 1:15 scale and has sound effects.
For most collectors Sunstar and DST BTTF DeLoreans would seem pretty accurate, but they do have some inaccuracies which are pretty major to the obsessive BTTF fans.
One of the most glaring inaccuracy is the side wiring; which should not go above the tires. And the three cylinder capacitors should be red in color and not grey.
These two details used to bug me all the time. I wrote to Sunstar and DST early on, they acknowledged their mistake but didn't bother to fix them. Sunstar did fix the red color but not the wiring for their final BTTF 3 Railroad DeLorean model. Hot Wheels thankfully got those details right.