Are you talking about the panel being inside or outside? Inside by the front door is ok, especially since that usually means you are next to the panic button when you open the door.

Also, you can have more than one. I have one inside the back door where I enter the house from the garage, and another in the master bedroom. Also keep in mind that you don't need one close to where you come into the house...you just need to be able to walk to it within the delay period and without setting off any non-delay sensors within the house.

If you are talking about the main "control box" with the "brains" of the system, put it anywhere you want-
Usually in a closet, up high, no need to service it too often, except for battery change out.

If you are talking about the "Keypad", then near your most used entry/exit door is a good place, and I would suggest a secondary one in the master bedroom. That way you don't have to walk far if you forgot to set the alarm at night, and also will have a "panic" button/duress button readily available should you need it if something goes "bump" in the night!

If you are talking keypads I definitely recommend 2, one by the entrance you use the most, and one in the master bedroom. My alarm went off one morning at 4 AM and because I had the keypad in the master bedroom I could immediately see it was the glass break alarm in the kitchen which had alarmed. That was somewhat reassuring because that alarm goes off with any loud noise, and was quickly able to determine the cat had knocked a can of tuna off of the kitchen counter onto the floor. Darn cat, lol.

A little off-subject but on Amazon you can get small magnetic switches that can be re-purposed for door-locked indication. You drill a 1/2" hole straight into the deadbolt pocket, a second 1/4" hole at a 45 degree angle at the point the door trim meets the wall so you intersect the 1st hole. Install the switch threading the wires out the 2nd hole. Wire them in series with the alarm door closed switch, Cut the magnet part open and you will see 4 'super magnets' stuck together. Sand the end of the deadbolt rough and epoxy one of the magnets to the end of the bolt. It will stick magnetically but the epoxy will keep someone from taking it off. A little silver paint and you'll never notice it. Now your doors will have to be closed AND locked before the alarm will set.

Here is a link that might be useful: Mag switch

Switch in deadbolt pocket

Wires coming out of wall.