Even though A breastfed into toddlerhood, we still had to have a system to deliver milk and (later) water into her little belly. Bottles were the obvious choice when she was little, but we preferred not to send her to preschool on a bottle. So, we had to find a sippy cup system that worked for us.
The issue with average sippy cups is that she had difficulty getting it tilted up high enough to get the water at the bottom when she was super-little (even though she'd had it down with bottles? I don't get it, either). I researched a bit, and found a pretty decent solution - the Tilty Cup (LINK). Basically, it has a diagonal shelf that divides the cup in two in a way that's pretty ingenious - it keeps the fluid high so that the child only has to lift the class part-way to get out their tasty drink. The problem? It looks sort of like this when you set it down (except I think the spout is actually on the other side - anyway):
That would be copious amounts of milk (our milk really isn't that color - usually) spraying out the top and landing all over the table, floor, your lap, whatever. My daycare provider at the time wasn't the world's biggest fan of this one. So, I'd say we used it for about three weeks, just until A understood the concept of tilting her cup. Since they're roughly $28 for two of them regularly (although we found a sale on Amazon), this was not a stellar deal. I'd probably only go this route if you don't mind your house looking like a dairy exploded all over it. It was useful, but not $28 useful.
Next we went to a NUK sippy cup with a soft spout, because A was so used to nursing or bottles that she really needed that soft spout. Here's a LINK and a photo, they run between $5.99 and $9.99:
These were pretty great, she had two handles onto which she could hold. Here's a photo of her at just over a year, able to navigate this with a broken arm (that was terrible, by the way):
Again, I'd say the cost at the upper end was a little extravagant for a drinking cup that will, at some point, be used as a throwing apparatus. It worked for what we needed it to do, though. The issue with this, again, was leaking due to the soft spout. A wanted some chocolate milk in one of these today, and it got ALL over her and her adorable little elephant chair - and she's three years old now, much better motor skills. So it's not like this gets better over time.
Within, say, three months or so, she was ready for a hard-spout cup. We are big fans of the Playtex insulator cups. We have approximately 70 that look like this:
At $7.99 for two, they're the cheapest of all I've listed. We get a ton of use out of these. They don't leak, they don't break when they're dropped/pitched out of the car, they have a hard spout that is durable and cleans easily. Here's A making a princess picnic, you can see her pink drank there in the midst of her fanciness (please note that the doll in the highchair at the bottom is apparently eating cookies and fuzzy pom poms):
Really, the only downside to these occurs if you happen to, say, leave one full of milk in the hot car for a couple of days, and you maybe only find it because of its smell. Not that such an instance would ever happen. Here's how the inside of one of these lids looks (the little plastic dealy comes out):
Now picture that plastic thing all caked in nasty, rotten, putrid milk. Appetizing, right? It washes out okay, but it always just seems a little funky to me. I think maybe there's a way you can buy replacements of these, I just haven't found it quickly offhand - but honestly, at $4.99 for one or $7.99 for two, they're not terrible to just replace if they're too awful.
With a future child, I'd probably skip the Tilty Cup and maybe even the NUK, and go for a MAM Learn-to-Drink cup (LINK). I'm a big fan of MAM (that's a different blog post), and that is a learning sippy that is spill-proof. They're also a little skinnier at the middle than some of the others, which is wonderful for tiny, pudgy little infant/toddler hands. Once that's outgrown, we'd probably stick with the Playtex Insulated. Hopefully we reproduce more girls, since pretty much everything we own is pink.