So what is the leading choice for a pid controller for my new Kamado grill?

Ive used a BBQ Guru DigiQ for about 6 years now with no complaints. Still using everything that came with it. They make bluetooth and wifi versions as well. TBH the DigiQ runs everything so smoothly that the only use I see from those more expensive versions is the data you'd get on your cook. Admittedly, this would be interesting to me because I cook briskets sometimes when its 70 degrees overnight and sometimes it's 10 degrees overnight.

I have noticed that you really need to use good quality charcoal (Fogo, Jealous Devil, Harder Charcoal) vs cheap (Cowboy, Royal Oak, etc) when you do a long cook with the controller. It does tend to run through more fuel than when I dont use it on shorter cooks like ribs and turkeys.

With a kamado, they all work about the same keeping temps set because of how insulated they are.

As NColoradoAg said, the price differences are really in the bells and whistles. All the popular ones will keep your temperatures really close to your setpoint.

Fireboard makes a really fancy one. It integrates Alexa or Google Assistant and everything is in the cloud and accessed via an app or voice assistant. You have to buy the blower fan separate and some other things are a la carte. For the drive and the pro it will be $300+ to have it all running and working. If you do not have Wi-Fi where the kamado is located, it works via Bluetooth but you lose some of the added features you are paying extra for.

https://www.fireboard.com/

If I was buying one, I would seriously consider Auber Instruments. They make some great controllers for kamados. Their kits are turnkey. Just select your brand and model and they will include a fan with the correct mounting adapters/brackets. Everything will fit perfectly out of the box. They also use RTD temp sensors for bot pith temp and meat temps. Each kit comes with 3 probes. 1 pit temp, 1 meat probe, and the third one is your choice between a traditional meat temp probe or a fish temp probe.

It looks like they are on sale right now for $225.

https://www.auberins.com/index.php?main_page=index&cPath=14_100

#3 is DIY. Are you a technical person? I built my own PID controller that uses multiple fans for an offset. It datalogs and even sends text alerts. I think I have one or two circuit boards left.

It is raspberry pi based and you will need to be able to solder a few surface mount components.

I did this to learn Python. It has cost more than any commercial option but it has been really fun and I have learned a lot about what really goes on during a cook.

I have been asked, but I have no desire to market this thing because I do not want to offer tech support to the masses.

I would like to share my code & schematics and have others build test modify and evolve this thing as a free open source community --- if anyone is interested.

Ive had an auber unit for 10+ years for my bubba keg. I was leaning towards their new version but wanted to see what else is out there.

I build a sous vide controller a few years of and the works well enough. I wanted something I could use with any heat source.

I might try building a raspi based one on a lark but all of my raspi stuff ends up in box or cannibalized at some point. So I wanted one I knew would would all the time.