Upvote:2
Advice on this is contradictory. If you look at the Schengen Visa Code, the rule defined in article 5(1)(c) is that you should apply to:
if no main destination can be determined, the Member State whose external border the applicant intends to cross in order to enter the territory of the Member States.
That's not ambiguous: You are touring several countries with no main destination so you have to apply to the first country you will enter in the Schengen area, i.e. France.
However, some consulates have invented a “first main destination” concept that is nowhere to be found in the actual regulation (where the main destination is a single country). This idea has made its way to some versions of the Schengen Visa Handbook edited by the European Commission, which gives it a bit of weight and makes the rules very messy.
Under that logic since you don't have a main destination, you should disregard transit and incidental visits and consider only the countries where you are spending the most time (so Poland, Austria, and Italy). They you apply to the first of these countries you will enter, in your case Poland, or maybe choose any one of them.
Because of this, I would not be surprised if Poland is fine with processing the application, even if it should in theory be France. I certainly hope the French consulate wouldn't decline to do it (but who knows with the mess the Commission has made…). Worse case scenario, you could bounce back between several consulates (I have seen a few example of that) but they do have a lot of leeway so common sense may still prevail.
If you can afford it, @Traveller's idea to add a day in Poland to sidestep the whole issue is also a good one. You said you want to spend “almost“ the same number of days but if your stay in Poland is longer even by one day, it will look like the main destination and nobody will ask questions.