There's no such thing as the best provider. Every VPN has their advantages and disadvantages, it really depends why you need it. Could you specify this matter?
I read THIS article today that could help you choose. I doubt there's a good offer for a 6-month subscription as most VPN providers offer 1 month / 1 year / 2 yearplans, but if you don't mind spending a bit more money, Surfshark is a good option. I got them for $47.76 24 month plan with the discount code -surfdiscount