wat are some pros and cons to using just one of these?

do the pros outweigh the cons?

It limits you.

Although it isn't always the case (and there are many exceptions), crankbaits are good searching baits and cover a lot more water whereas soft plastics are usually slow moving, "methodical" baits for working a smaller area thoroughly.  Soft plastics are generally more appropriate for days when the fish are neutral or disinclined to bite and are tucked deep in heavy cover whereas a crankbait can call in fish from some distance.  IMHO, there are far more pro's to having both than cons.

I think hard baits are fun.

I will always choose a hardbait over a soft plastic to try first.

That being said, my experience is that soft plastics outfish hard baits by a wide margin.  

On some bodies of water, like my favorite pond, the bass are sometimes TOTALLY focused on baitfish. When this is obvious, hard baits always outperform soft plastics. In low light (morning and evenings) this is usually the case, too. For me, soft plastics and jigs are most productive "during the day".

8-)

I think hard baits are fun.

I will always choose a hardbait over a soft plastic to try first.

That being said, my experience is that soft plastics outfish hard baits by a wide margin.  

x2

I look at it like there's the 'BIG 4', and everybody usually prefers one over all the rest...There are:

SpinnerBaits (including Inline spinners and buzzbaits), Soft Plastics,

Crankbaits (including topwater stuff like poppers and things like hard jerkbaits.) and Jigs

Then there are crossover baits, like the soft jerkbait (flukes sluggos, etc) soft swimbaits (Magic Shad, or similar) and buzzfrogs.  These all are 'soft' but fished like a spinnerbait or a crankbait...

Whatever classifications you make, some anglers usually prefer one, or two methods over the others.  

I prefer Crankbaits, and throw them far more than anything else.  Many times I will throw a crankbait as a searchbait, and go to a suspending jerkbait to work a fish producing area more thoroughly.  Sometimes then I'll go to a soft plastic...

When I am not fishing cranks, I prefer spinnerbaits.  I only reluctantly throw soft plastics as a first option, and even then I prefer to throw a soft plastic 'crossover' bait like a Cane Toad or a Sluggo.  

I fish with a lot of friends that use nothing but plastic worms, and some days they beat me, some days I beat them, but usually there is not that much difference and we break even.  A lot of it depends, I think, on the competency of the angler - I will throw the same soft plastic they throw, and watch them catch 5 fish to my 1 on the same exact bait.  Or, they will put on a similar or identical crank that is producing for me, and the opposite happens, I catch 5 to their 1...

I like to think I am very good with a crankbait, but I know I need to get much better with a soft plastic.  But I'm lazy, and fishing time is precious because I have three kids and a demanding wife, and so I follow my strengths, and usually do well enough... I don't think my success/theory would translate to tournament success, but those guys are usually really well rounded, but I do pretty good, as good as anyone I know or see.  I remember some pros that used cranks much more often than not, like Denny Brauer and David Fritz.  Rick Clunn uses a lot of cranks too

I have caught one fish on a crankbait and a gazillion fish on soft plastics. That's pretty much the difference for me.  

Ronnie

I tend to focus more on using soft plastics----most of the time.  That being said, I always have a little variety tied on 6-8 rods.  I tend to focus on soft plastics because in my experience I can often catch them on that when they are also hitting cranks, jigs, or even top water.  But not necessarily do I find the reverse true.

Lots of times I find that I can switch between soft plastics and a crankbait or vice versa and have a slowed bite pick back up.  Guess the point is that don't get stuck on one method, sometimes a change is what they are wanting.

Studies have proven that the plastic worm is the only lure made that a BASS CANNOT REMEMBER!

That is, a bass will continue to strike a worm even after repeated catches, whereas a bass will "turn off" to other lures, spinner baits and crank baits etc. after wearing them out on them. That's why you cannot continue to catch them on your honey hole with the same lure over and over. Bass will stop eating that which will eradicate them. Not true with the plastic worm, however. Although we all know bass will prefer a different bait at different times (i.e. "the pattern") you can always go back to the worm to catch them.

I belive that if you can find fish in an area where a crankbait can be presented it is by far the best bass lure ever.   In natural northern lakes bass spend most of the year and most of their time buried in heavy vegetation or under brush, and you can't generally fish a crankbait there.  

If you can catch find fish on the edges you can clean up with a crankbait.  The good news is when bass move to the weed edges they are usually agressive which maybe the reason the crank is so good.  

I have to go with soft plastic as being better than crankbaits.  It seems that when fish are hitting crankbaits they just can't stop. But when the bite gets cold, I go to a Senko or some other type of soft plastic.