Need help with choosing primer
The kind or brand of primer does not matter much.  Most products perform equally well or equally poor.  The biggest payoff is in the prep-work.  Even the "best" primer cannot adhere well to a wall that is covered with sanding dust or loose texture.  Wipe and vacuum everything.  Otherwise your nicely painted work might easily peel off with just the tip of your thumb.

If you have visited the paint section recently, you have probably seen that the price of primer and other paint products vary a lot.  Usually that's just marketing at work.  The exception however is Volatile Organic Compound (VOC) content.  These are the things that the State of California has found to cause harmful health effects.  So-called "low" VOC products have less than 50 g/L, whereas "Green" products typically have zero.

Unless you are painting  specialized work (nautical, plastics, automotive), or if you have a particular health concern (pregnant mothers), there is really no need to go with anything other than the cheap stuff.