There's things I like and dislike about both. I went from an X to a 4s, and it's ridiculous better to me, but it honestly depends on what the person wants.
I liked how I could customize my X (down to the keyboard, etc.), but at the same time, it sucked when something at the stock level was so bad, that I had to go search for a better version and replace it. Most built in functions on my 4s are great right out of the box.
I don't like how "controlled" I feel with my 4s, though. That'll be solved in a few days, though. Jailbreak should be out this upcoming week. I'm conflicted about the screen size. I prefer it for texting and things of that nature, but for browsing the web, playing games, etc., I'd rather have a Droid's increased size.
I like the end-to-end integration that apple provides. Sure, Android tries to sync everything, but it's sloppy at best.
I also dislike the support, in the form of software updates, that are provided for Android phones versus Apple phones, which is a product of all the different manufacturers and quantity of phones released, whereas Apple has a set of like 3 or 4.
I also find that my battery life is much better on my 4s than my X, which I'm attributing mostly to Motorola sucking.
I had a pretty negative experience with my Droid X, but my GF has a Galaxy S2, and I think it's great. She has had a few issues with it (requiring a factory reset), but it's a great, no lag-filled, no random-rebooting experience, which is what I got with my X. I think the most important thing when getting an Android device is to choose the right manufacturer. From what I've heard, Samsung is the only one that gets it right.