I've been looking at different hardtail 29ers and noticed that there are basically 3 types of front suspension forks: Suntour, RST, and RockShox on sub $1000 bikes. Looking for some opinions on which of the 3 is a higher quality fork. Also wondering why some bike manufacturers use 80mm forks and others 100mm when they are in the same price range.

Those are brands. Each brand will make forks of different quality levels, so you really need to know the specific model. For example, I'd take an RST Space Jump over a RockShox Dart any day, but a RockShox Lyrik will kick the crap out of an RST Launch. Most of the time, the Suntours and RSTs that get put on entry level bikes are crap, though RockShox Darts really aren't that much better (if they're even better at all).

I would generally go for Rock Shox if I had a choice between those 3. Would be great to link us to the bikes you are looking at.

Here are the two bike I have narrowed it down to. Both would have to be ordered through my LBS since he doesn't have them in stock. I was also considering the Giant Talon 29-0 but I just don't like it for some reason. Prices: Felt $999, Jamis $1100

https://www.feltbicycles.com/USA/2012...ine-Sport.aspx
https://www.jamisbikes.com/usa/thebik...comp_spec.html

The Jamis has a slightly better component group set on it (which is expected seeing as it is $200 more), and in my opinion would be a slightly better bike, but what matters is which one feels better to you while riding it. Go test ride both of them and see which one you like more. Both of them would be considered quality entry to intermidiate level bikes.