as an PhD student with salary you have 2 ways to go when it comes to getting unemployment benefits after you finish PhD as you also mention yourself - as an employee or as an graduate.
First of all you have to take into consideration that the unemployment benefit (rate) is lower for graduates compared to the rate you get if you are "normal" salaried member of an A-kasse.
And this difference har increased from january 02, 2017 because of new rules/law. Before 02.01.2017 graduates got 80% of the maximum benefit rate, now graduates who have dependent children, only get 71,5% of the maximum rate.
You have dependent children, if you have the obligation to contribute to a child (or children) under 18 years who are staying in Denmark. Are you EU / EEA citizen, you are considered also as a parent if the child resides in an EU / EEA country.
As an salaried you can get 90% of your salary, but maximum (DKK 220.740 per year). In this way most salaried will get the maximum benefit rate.
This also means that as graduate without children you will get DKK 157.820 per year.
So even if you have to pay for membership for one year (equals about DKK 5.500, which also ix tax deductable) then it will be best for you to register as an employee and pay for your membership.
BUT this is according to the current rules about how you can earn the right to being eligible for benefits. From juli 01, 2017 also the rules/law about how you earn the right to being eligible for benefits will change.
From that date it is NOT the working hours (1.924) which is important anymore. From 01 of july 2017 instead you must have had an income of DKK 223.428 during the last 3 years/36 moths before you get unemployed.
And now it get a little complicated: because only income from periods where you have been member of an A-kasse is counted, and also there is a second condition that says that the maximum amount/income per moth which is allowed to calculate is DKK 18.619. So everybody no matter your income must have worked for at least 12 monts during the last 3 years before being eligible for unemployment benefits.
Income and/or membership periods from other EU-countries can be used in the calculation. So if you have been member of an Unemployment Insurance Fund in you own country and during the memberperiod have had income then you can take this into account when calculating your right to benefits after the danish rules.
We assume you have not been member in your own country:
So it is up to you to calculate what is possible for you. If you are able to register now for membership and pay 12 months and in the same 12 months will earn at least 18.619 per month, then you should register as an employee.
If you are not able to have the next 12 months with income every month for at least DKK 18.619 then the only way for you is to register as an student and only get the graduate rate.
Please be aware that this is new rules and therefor we advice you also to ask your A-kasse about the same things before make a decision.
Hope it clarifies,
otherwise please make a comment.