Who is the best and cheapest ISP in New Zealand, and why? How do you think of internet providers in Auckland?

It's a moving target. In general however, the smaller ISP's will have better, more personal customer service, and so if that's important to you, go smaller. In addition, the big ISP's don't always have faster speeds - as the results at TrueNet - The broadband monitors will attest. The "Best" ISP for you, may not be the best ISP for someone else, so it pays to do your own research. (disclaimer - I currently own www.voyager.nz, and I was the original founder of www.orcon.net.nz )

There are various criteria to say which ISP is the Best. It depends on each person.

Speed
Good Plans and offers
Low Cost
24/7 customer Support

But most of the Internet service providers which fails to engage better with their subscribers are not the best

Low uptake of VAS
Poor communication with the subscribers through mail, which fails big time.

So the ISP and network operators using In-browser notification for their subscriber engagement which works in all browsers showing Bill payment Due, Date reminder alerts , recharges , offers etc without help of an app and interrupting the subscriber and reducing the subscriber churn using their new industry standard in-browser communication tool

ISP for residential or business? The answers to each are very different. Also 'best' could cover a number of different parameters which will vary from individual to individual - service, speed, cost, etc. One observation I've made is that service from all the larger companies is less than stellar in comparison to some of the smaller ISPs such as Snap (whom I've heard many good things about from a service perspective).

Residentially speaking, there are options outside of ADSL worth looking at such as wireless (I'm involved with a wireless company) or cable. Whilst not available to the same degree as ADSL, performance is generally better (~2ms latency to APE/WIX in Auckland/Wellington for example) and value for money is worthwhile.

Business connections are often fibre or wireless, with both Auckland and Wellington having extensive coverage of both. I'm biased (although for good reason!) but wireless generally has cheaper install costs, less minimum contract term and lesser ongoing cost, with comparable performance suitable for almost any business.

Ultimately, there will be tales of woe about all ISPs, so keep an eye out for helpful answers with specific experiences and examples, talk to friends and family, and even test drive an ISP's service beforehand if you know someone who uses them (taking into account that different addresses will have different performance due to line quality, distance from exchange/cabinet, etc)

Our business depends on uninterrupted high speed internet so we have switched to Telecom as they actually own the lines.  When there is a breakdown, Telecom is faster to react than going through other ISP's who then have to contact Telecom.

Snap - www.snap.net.nz

Excellent customer service, great product offerings. Internet Service Provider of the Year at both the 2010 and 2009 TUANZ Innovation Awards.

One more vote for Snap.net.nz.

Nice people who know what they are doing.

Definitely the best for both-way speed and data I could find.

This question is entirely subjective however, I have used Telecom ( they were positively rude after twenty years with them), Vodafone, whose service was excellent but whose costs were high, so it's Slingshot for me, unlimited data means I don't have to worry about going over my cap, there is little in the way of customer service but then I haven't needed to speak to them since I joined, my service rarely goes down and my speed is slightly better than with my previous ISP.

Going through a cabinet means there is little speed difference no matter who I choose so in the end it came down to data allowance, hence Slingshot.

It depends on where you are living. As Mauricio mentioned earlier, if you're in CHCH or Wellington then Telstraclear is the best.

In Auckland, I have found that there is not much difference between providers in terms of speeds. The point of difference for me are the data plans and the customer service of course. Over the last few years, I have had Telecom, Vodafone, Slingshot, Orcon & Telstraclear. There's not a huge difference in speed/reliability between these providers. I liked the Vodafone & Telecom customer service.

I recommend any of these providers. Choose a data plan that works best for you and sign up.

Snap
Fast, very competent and reliable. Great price as well.

Maxnet
Great Helpdesk (biased as I did run their Helpdesk for a while). They are fast and reliable.
But their prices are expensive.

Voyager
Very fast, reliable and good pricing. Allows Ipv6 and multiple IPs

Orcon
They are fast and have good prices, reliable. Helpdesk is ok but often overloaded.

Orcon - offers ADSL broadband, VDSL broadband, and naked ultra-fast broadband;
Spark - offers 60 GB, 120GB, and unlimited plans;
2Degrees - offers 80 GB and unlimited plans;
Vodafone - offers ADSL, VDSL, fibre, and fibre X plans;
Trustpower - offers ADSL, VDSL, and fibre plans.

The NZ's best broadband providers 2020
MyRepublic. 24 plans 5.0 /89 reviews.
Stuff Fibre. 5 plans 7.0 /56 reviews.
Orcon. 4 plans 5.6 /143 reviews.
Slingshot Broadband. 31 plans 5.9 /149 reviews.