A list of what to consider when choosing a vpn provider :
1. Company country base
It's important because different countries have differnet laws about keeping logs and privacy.
Avoid 14 eyes countries
if goverment agencies are a great concern for you.
2. Log policy
The ammount of information, if any ,the vpn provider stores(log files) about you.
This is in direct relation with the country based company aspect described above.
3. P2P traffic
Some vpn providers allow and some do not allow p2p traffic.Also some providers allow p2p traffic from certain server locations
and forbid from other locations. P2P traffic is important and you should carefully examine each provider about it.
4. Connected devices
There is a number of devices you can connect for each account and this is important. Most of people use more than one device to
connect to the internet and its good to be able to use a vpn to more than one device.
5. Plarforms supporting
Although nearly all vpn providers support all os (mac, windows, ios, android etc) platforms its good to check it before subscribing.
6. Refund policy
It's always better to test any service before you buy. Most vpn providers have a refund period and this may vary among providers its advisable to chek it before you choose.
Make use of it if you are not happy with the service.
7. Additional information like
Encyption protocols, kill switch and dns leak protection, payment methods and support level are things to considerwhen choosing a vpn.