You give far too little information, and are asking people you don't have any reason to trust. 🙂 Don't get me wrong, get as much information you can, but only use us as one source of information.
A few things to think about.
What are your objectives for cycling?
In what ways do you think your bike is limiting you, as opposed to the rider being the limiting factor? 😉
Is there anything causing a lack of comfort, or that you just don't like the looks of?
What is it that makes you think that anything needs to be upgraded? Or are you responding to marketing and peer pressure?
If you ride with someone and can't keep up with them, and they ride the same size bike, see if you can trade bikes for a day... can you keep up after the trade? (I think not!)
Ride what you have until you are ready to upgrade to a better bike instead of keeping yourself broke upgrading the bike you have... If you feel the need to upgrade your current bike, upgrade as something breaks or shows signs of wear, that is the most logical approach, and it will keep your bike maintained as well. Think upgrades in conjunction with maintenance rather than upgrades for the sake of upgrading.
But, if you simply must upgrade for the sake of upgrading, wheels are one of the common things to upgrade first.
To get a reasonable recommendation for wheels, you should let people know what type of rider you are (racer, commuter, tourer, charity rides) what type of roads you tend to ride (rough, smooth etc) how heavy you are, whether you are looking for durability, comfort, speed etc...