I'll throw my hat into the ring on this one, I recommend owning three colour types depending on the conditions.
Light natural colour (white, blue), a darker colour (black, olive) and a brighter colour (pink, orange, green).
My go to is:
Clear water, full sun = natural light colour, white, pilchard, silver whiting or anything close.
Clear water, overcast = natural dark colour, olive, black, rainbow foil.
Murky water full sun, = natural dark colour, olive, black, rainbow foil.
Murky water, overcast = bright colours, pink, orange, bright green.
Sunrise = pink, sunset = orange. You can get away with the natural/darker jigs depending on light too.
I pretty much use this chart when picking my colours depending on the clarity and light levels.
Yes! Squid are colour blind, but do see UV Light. Contrast is key. More about the Science of Squid fishing :
viewtopic.php?f=14&t=24800
Size wise, go whatever works best for where you're fishing. I fish St Leonards and only use size 3.0, perfect size for our depth/conditions.
Every place is different.
I'd love to say I'm unbiased when it comes to brands, but I've only ever used the Yamashita Sutte-R jigs. My experience with these jigs has been nothing but positive and I feel the range of colours and cloths offered in that series is pretty incredible. I would say for the the price, when on sale, these are top quality jigs. Over 100 squid on one of my jigs and apart for some tearing of cloth she's working as flawless as they day I purchased it.
IMPORTANT Yamashita Sutte-R 3.0 jigs retail @ $16.99 at BCF excluding postage, do not buy them there. Dinga which is an online Australian seller sells them at a normal price of $11.99 free postage. On sale at Dinga they can be as cheap as $8.99 free postage. Last weekend Dinga had size 3.0 Yamashita Sutte-R jigs for $8.99, they often go on sale. Jigs can be very very expensive, the only time I'd pay for something more premium is for a rattle, or maybe that flash boost. That said, out of the eight jigs I own, none have either. haha