Well, since you asked ...
I would have gone with a straight winged arrangement because;
1. tanks aren't the most streamlined objects, so are unlikely to travel quickly in the air;
2. tanks are heavy (even if made of styrofoam & fibreglass) & the CoM* is kept over/near the CoL*;
3. it gives you more options (twin-boom [with/without engines in the booms], single fuselage shell [probably with two "keels" running along
each side & room for internal fuel tanks], box-kite with multiple engine positioning options [top wing/lower wing either under-slung,
over-wing or mid-wing, or suspended within the box-kite frame]; &
4. straight wings have a lower stall speed than deltas & tank tracks aren't optimal for fast running, so a lower landing speed is better suited to
the vehicle.
Just my opinion ... & a bit of playing Devil's advocate.
It's your build, mate, do what you like & have fun! :)
(CoM = Centre of Mass, CoL = Centre of Lift)