Hi Colin,
I use a range of chemicals for per sprays.
Firstly you will find the powders better value for money.
Ones I like. Prochem power burst, good for bar, restaurant and polypropylene in rentals. Mix 7 scoops to 5 litres for heavy soiling. Pre spray gold is overpriced and not strong enough.
Solution have spm. Which is very good. And self neutralising. Medium soiling and good on wools.although use acid rinse on wool. Also you can bonnet buff with this, plus use on fabrics too!!!
They also do shock wave for heavy duty stuff.
And m-power is good to.
Chemspec make good products but are slightly on expensive side, and quite a few liquids.
Best to try a few, none of them will let you down, and you will find what you like. Also depends what sort of work your doing. Domestic high end, eot cleans or commercial, as its horses for courses.
Mark