re: Any woodworkers out there that can tell me which pocket hole jig I should buy

Pocket holes are useful within their limitations and as mentioned you need to use the correct pocket hole screws for the thickness and type of wood you are using. They do NOT have to be Kreg branded and McFeely's carry quality fasteners.

I have an old K3 but it was discontinued because of the clamp having some patent issues. It was better than the K4 (because of the clamp) but I haven't used any of the newer versions. The Kreg jigs work well and parts are easy to obtain.

Not really useful for the OP but in case anyone is looking for a higher quality pocket hole solution like if you are building a full set of kitchen cabinets or a lot of boxes for built-ins take a look at the Castle versions. The Castles produce low-angle pocket holes and significantly reduce assembly time because they don't require clamping like the high-angle pocket holes Kreg and everyone else uses. The angle prevents the screw from trying to pull the boards out of alignment which anyone that has used high-angle pocket screws will have encountered. They also rout the holes instead of drilling them and are faster and cleaner. Again they are not for the budget oriented but they have a better approach in case someone is searching here. You can occasionally find the table top ones on Craigslist and they are powered by Bosch router motors so motors are easy to source.