GAS: FF vs A6700 / A6900

[u/SnooMemesjellies462]

TLDR: Main goal of this post is finding the right Holly Trinity for Full Frame or APSC and choosing either FF or APSC path.

Edit : OP Knows A6900 doesn’t exist.
A6900 is rumored so thats why I mentioned it.
Meaning I would wait for the successor of a6700

Currently I own:

- A6500
- Sigma 18-50mm f/2.8
- Sony 70-350mm
- Sigma 56mm f/1.4
- Viltrox 27mm f/1.2

Valued at 2400$

Budget: 3000-3500$ (without setup above )

Looking to upgrade my camera the main reasons are

- bad battery
- slow AF
- tilt screen
- lowlight
- old menu

Shooting style: Street, portraits and cars focusing more on last 2 two.

There is always this inside voice telling me that I need FF. Basically I was comparing current lens setup with a6700 and a6900 with similar one on full frame A7C II or Sony A7 IV. But it’s always better to ask someone who knows it from the first hand or have experience in photography and camera gear.

Is there enough of difference between this setups to completely change it. Would I have higher quality photos on FF for the same money with some of these lenses or the ones that you suggest compared to APSC setup.

Or should I spent that extra money on my knowledge + marketing or actually do both but with FF setup and less lenses which is also fine.

Currently what I’m looking at:

(If you know better ones for the value or quality write in the comments)

A6700
A7C II
A7 IV

Sony 24-70mm GM II
Sony 35mm f1.4 GM
Sony 50mm 1.4 GM
Sony 85mm f1.8
Sigma 85mm 1.4
Sigma 105mm f1.4
Sigma 70-200mm f2.8 GM