Honestly it depends on what you are looking for. I prefer to change my credit card once a year because of the offers that you can get. It doesn't do much damage to my credit, and I pay it off every month.
AAdvantage has the best promotion if you are wanting to do something like go to Hawaii. Get 30K Frequent Flyer mile points after 3,500 spent in the first 3 months. First year fee is waived. Coach tickets to Hawaii are 17.5K for a one way ticket. Get a card for you and a separate for your wife and you have a trip to Hawaii. First Class is 24.5
Southwest has a promotion right now that you can get 50K for a personal credit card and 50K for a business credit card. If you qualify for both that can give you 100K points on the start. This is enough for 4 round trip tickets. Also, if you can accrue 110,000 points in a year you get a companion pass. This is where for the rest of this year and next year for every flight that you fly with southwest you get one ticket free.
US Airways gives you 30,000 after 3,500 spent in the first three months. This isn't enough to get you to Hawaii and back. That takes around 40,000 points. Their bonus is that you get 2 companion passes immediately. $99 a piece. So if you get to 40K then you can take two people with you for $200.
Chase ink just ended a promotion giving 2% cash back and you get 30,000 points if you spend 5,000 in the first 3 months. This equals to them paying you $600. Not sure what their new deal is now, but you need to get at least 2% cash back on any card if you want to go this route.
If you are looking for a hotel credit card I suggest you look at where you are wanting to go and check the promotions offered for that city.
To answer your question my wallet has AAdvantage in it. They did a promotion that I took advantage of and got 80K points.