What to upgrade first: Driver, hybrid or wedge?

Driver: Don't forget the shaft. Any chance you could get on a launch monitor and see which shaft works best for you, the best mix of altitude and carry? What is your hand size? If you went from slices to a hook, any chance you could use a slightly thicker grip? If your grip is too thin, you could have extra hand action that rolls the clubface closed and delofts it, leading to hooks and low shots. Consider if a thicker grip (and maybe shorter shaft) could help you keep the Nickent in play.

Also, you don't give us much info to work on. What is the loft of your driver, and the shaft model / flex / weight? And, what is your driver clubhead speed?

On Cleveland: Although I didn't buy one, I liked the Cleveland Classic 270 / 290 / 310 family. Be aware that lots of 270 models are still in the stores, in part because the shaft is too light for most golfers. A too-light shaft can cost you control (hooks and others), as can a too-long shaft.

Hybrids: Others can address this.

Wedges: Don't automatically badmouth the Tom Watson wedges. They cost $30 because they are a mature model, and Adams doesn't have to advertise as much or do lots of testing on the heads. Unless you do a lot of trick shots in your short game, the TW line could serve you well.  The TW offers a 52.08 GW, a 56.12 SW and a 60.07 LW, standard lofts and medium bounce grind. Lots of golfers do quite well with this mix.

Be cautious about buying used wedges online. You don't get to test-hit them, and if it turns out they're used up rather than just used, you're stuck with them.

I would look into the hybrid...I know that it made a huge difference for me. Turns out Taylormade's stock shaft worked wonders for me. I know that if you get your hybrid working well for you, you will have better scoring opportunities on long par 3's and par 5's. It also can be a game saver for you on short par 4's when your driver or 3 wood isn't being very helpful to you. Of course, in these scenarios, I would think that you would want to put a 3 hybrid into play. You can pick them up with scratched paint if you don't worry about that kind of thing with lots of life in the head and shaft. 

I would say to upgrade the clubs you use the most. For most beginning golfers/higher handicappers, the clubs we use most often are the putter and the wedges (because of low GIR rate), and improving wedge play is one of the easiest ways to improve scoring. I was in the same situation as you and I found that when I got a new sand wedge that I had confidence in to hit a variety of different shots from tough lies, I really improved my scores. I know you might think this club is pretty ugly, and anyone who is seen on the course with it is bound to receive some heckling, but the Cleveland Niblick wedge is a very reliable, versatile club that you can use for a variety of shot types. Even though its ugly, people who use it rave about it because it will save you when you screw up, and it can be had for REALLY cheap. Maybe it is something you could look into for replacing one of your wedges. I know that it is on my list of clubs to acquire, even though I'll be made fun of for a while.

I would guess that you probably don't use your hybrid too often, maybe for 2nd shots on long par 4's or on par 5's, which probably occur between 4-6 times per round. Your driver you probably use 10-14 times per round. Your wedges? As indicated by your index, probably between 10-12 shots per round. So I would recommend the driver and wedge to be the first clubs you upgrade.

There is pretty good review for the Niblick on the Hackers Paradise, I tried posting the link but it wouldn't work for some reason. Google it if you're interested.