Grip Replacement- 
Replace your grips regularly, at least every year if you play or practice a lot. This is not horribly expensive, even you want OEM "logo" grips. I charge only $26 for my shop time to re-grip a complete set, plus the cost of the grips, so figure under $60 total.. It is perfectly reasonable to replace the grips on only those clubs that you use most, and hold off on those you have not used a lot. 

One grip manufacturer's ad encourages golfers to replace their grips every 10 games.  That's just goofy.

Grip Size- 
The size (diameter) of the grip needs to match your hand size. Undersize grips can cause unnecessary injury to your forward wrist. Oversize grips may feel good at first, but restrict your impact speed and control.  Arthritic golfers, and those with some other joint problems, find oversized grips more comfortable.

A 64th of an inch in grip diameter is equal to about a third of an  inch in hand length. Ideally, the tip of your closest finger will just graze the heel of your palm when wrapped around the grip. After-market grips come in x-small, small, men's and women's standard, mid-size, and jumbo sizes, with typically 2/64ths between sizes, and the grip's original size can be even more finely adjusted during installation, to fit your hand perfectly.

Off-the-shelf clubs come with "standard" size grips, for either men or women. OEM replacement grips usually do not come in other than "standard" sizes, but I can put some build-up material underneath to adjust them to your hand-size, if you need a larger grip size, and I can even adjust it a bit thinner if needed.  If your hand is less than 6-3/4 inches long (for men) then your should avoid OEM grips, and for that matter, off-the-shelf clubs.

Layered grips
Some of the better grips are now made in two layers. The inner layer is of a material chosen for its low torque and high shock absorption qualities, while the outer layer is designed for a soft tacky feel in your hand. That more than doubles the price, but they're still dirt-cheap, and worth it.  They take a lot of the sting out of severe mis-hits. 

However, many single-layer grips are also excellent, and to me at least, provide a more direct feel of the impact with the golf ball.

Grip Feel- 
Most average golfers prefer a soft, tacky grip. The design is not important, as long as you have confidence in it. But even a very good quality grip will lose its tack after a few hundred swings.  Most grips will also get harder and slicker with time, even if you never use them.  So grips need to be replaced fairly often, at least every three years, and every year if you play a lot.

Grip Torque- 
Every grip twists a little just before impact.. but so does the skin on your hand.  A grip's torque is not significant for most golfers. Most likely, you have already learned to compensate for this in your setup or swing. Some very good golfers find this to be an accuracy issue and prefer the stiffer "cord" grips.