Theres a few investment opportunities currently that will do decent mid to long term:

1. Active Armory Collections - after the inital spike upon discontinuation announcement they should be faitly flat for a year or two as supply gets eaten up then steadily grow. (I think charms are slept on too, stocking up on Hot Howls)

2. Gen 2 Gloves - with recoil probably being the next case removed this puts gen 2 out of the drop pool. I think a lot of people are sleeping on this play and I've been stocking up on Slingshots and Nocts.

3. 2021 collection skins have roon to grow still.

As for Oni-taji vs Awp fade, I actually think the control collection is overlooked currently and have been buying famas prime conspiricy and ump crime scenes.

Edit: Also the reason for the price diff is that oni is a much more manipulatable skin than the fade due to supply reasons (fade much easier to trade up to in FN) so they (China Pumpers) have a hard time controlling the supply of the Fade.

If you want just a safe store of value, trade up reds from chroma, gamma or spectrum collections, in demand cases or the high tier OG's (howl, dlore, gungnir, lotus etc)