More transfer/redemption partners = a good thing
Yep, that pretty much sums it up, and it's why I always tell my friends to go with either a Chase (ideally the Chase Sapphire Preferred® Card), American Express (Premier Gold/Platinum or EveryDay Preferred), or Citi ThankYou (Prestige) card for earning the bulk of their points (compare these rewards credit cards here). Why, you ask?
Take this recent scenario: I was booked from DXB to FRA then on to BKK, all via
United points. Turns out friends will be in Shanghai for a birthday and I need to join (well, really really want to join). If I were just a United MileagePlus credit card guy, I'd be stuck with flights like these to get me to PVG - both not very good options in my opinion, but representative of what was available when searching on United.com:

Overnight, MIXED CABIN flight for 60,000 points. No thank you.

TWO stops, MIXED CABIN for 110,000 points? Nah, I'll pass.
My Delta points? A total no-show here. Sure, when I use my Delta SkyMiles Reserve card from American Express I earn one mile for every dollar of spend, and 2 miles for every dollar spent on Delta airfare. But, even if award redemptions on Delta were easy, plentiful, and cheap (hint: they're not), I'd
still be locked into using all of these hard-earned miles on Delta, and in this case I was completely out of luck for getting from DXB to PVG. See
KVS Tool screenshot below:

No Business/First award availability at all :(
But,
Membership Rewards to the rescue! Emirates is now a partner of American Express Membership Rewards, which is great because I've found good award availability depending on the city pairs, and they have an excellent if over-the-top first class suites product, and an excellent business class product on their A380-800 as well. I don't fly Emirates enough to make earning points via travel viable, but with Amex I can burn my Membership Rewards points at a 1:1 redemption on Emirates. Here are the Emirates options:

A380 business class redeye.

773 first class day flight.
Sure, the taxes are higher than on the United fares, but Emirates gives you car service for both arrival and departure, which added to the additional luxury of a better hard product and a single direct flight, makes this a no-brainer.
In this scenario MR points gave me flexibility, and perhaps more importantly, saved me
time by allowing me to take a single redeye flight with no stops, and time might be the most precious commodity around. UR and MR points can be spent on
several airlines AND hotels, so rewards cards from these programs should be a staple in your point earning spend. Here are the latest options for each of these programs:
Chase Ultimate Rewards
- British Airways
- Korean Air
- Southwest
- United
- Virgin Atlantic
- Hyatt
- InterContinental Hotels Group
- Marriott
- Ritz-Carlton
- Amtrak
American Express Membership Rewards
- AeroMexico
- Air Canada
- Flying Blue (Air France, KLM)
- Alitalia
- ANA
- Asia Miles (Cathay)
- British Airways
- Delta
- EL AL
- Emirates
- Frontier
- Hawaiian
- Iberia
- JetBlue
- Singapore Airlines
- Virgin America
- Virgin Atlantic
- Choice Hotels (Clarion, Comfort Inn, etc.)
- Best Western
- Hilton
- SPG
- Hotel Gift Cards at: Mandarin Oriental, Hyatt, Four Seasons, Farmont Hotels, Aria, Bellagio, Marriott, Mirage, MGM Grand, Ritz-Carlton, Wynn, Mandalay Bay.
As you can see, that's a lot of options in terms of how you spend your points with these programs. In general, points typically have a dollar value of $0.01 per point, but I regularly extract $0.04 - $0.10 per point on airfare with various airlines when flying in premium cabins.
What else?
Which of these rewards credit cards do you like the best? How do you like to redeem
your points? Let us know in your comment below!