Food

As someone who should have made a career out of pickling and eating things (usually eggs and onions but I've recently turned my hands to basically anything that can absorb liquid) I can confidently say it is entirely dependent on personal taste and what notes and subtleties you want in there.

Depending on the vinegar used you're going to need a lot of aromats to break through though - people usually underestimate how much and just get a pickled 'thing' that tastes of vinegar and little else (which is totally fine btw).

I usually make the base liquid and add different things depending on what I'm pickling and what time of year - either extra christmassy spices or more sugar or different vinegars etc.

Something like:

1.5 parts water
1 part vinegar (malt or cider usually depending - malt a bit more christmassy, cider a bit cleaner)
1 part brown sugar (to clarify, this is a LOT of sugar).
sea salt (a good handful depending on how much you're making. I probably make 2 or 3 litres at a time so about 50 grams).

Then I'll add, variously, star anise, bay, peppercorns, cloves, fennel, mustard, cinnamon, nutmeg, maybe ginger, other, etc.

Basically chuck it in a stock pot and slowly bring to the boil making sure all the sugar has dissolved. Turn the heat off and drop the onions in and once cooled a bit add them to sterilised jars, seal and chuck in the fridge to test your resolve over how long you can wait before you eat them.