it depends. most of the time i play in creative mode (that's when i acuualy care) i use the wood native to the biome but i use surpus wood when i build medival style fortresses (you'd be surprised how often i do that)
Correction: Petrified oak slabs are uncraftable until release 1.3.1 and in 1.19.3, there are unobtainable in the creative mode menu until using commands.
no, the petrified oak slabs was introduced in Beta 1.3 alongside cobblestone slabs and sandsones slabs. These slabs are just a reskin of stone slab and was still craftable until release 1.3 when the <<bug>> was patched. There are still avilable in the creative mode menu.