I think having some easy AIO's would be a good addition to your stash. A couple less expensive ones I like are the new Thirsties AIO's (turn inside out to dry, just learned that), swaddlebee simplex (love me a side snapping diaper).
You might also want to try a hybrid system or an AI2 system such as Flips (cottonbabies). And, the shells are on sale now. There are plenty of other systems like this too.
It's all about trial and error, buy a couple of a few different kids, try them out, if you don't like them, sell and try something else.
I quickly grew tired of stuffing pockets and my whole stash right now is pretty much different kinds of AIO's and AI2's but I do occassionally buy a pocket that appeals to me.
Don't be afraid to buy used, just make sure it's appropriately priced (compare the cost of a new to the price they are selling used). Sometimes on here people will sell new diapers and they may be asking for full price, but generally they eat the shipping and I consider this a decent deal unless of course an online retailer will ship for free, then it's not great. Buying used is a great and generally inexpensive way to build your stash and try many different kinds. Also, check your local craigslist. I find really good deals on there sometimes.