Honestly, people go on Medifast for the quick results, not the taste! I haven't had Slimfast in a long time, but wasn't impressed by it. Medifast has way better nutritional stats, and isn't as sweet as Slimfast, but it doesn't taste like desert. I did Medifast for about 6 weeks and personally used the pudding mix to make shakes (along with ice, 1 oz. of fat free cream cheese), it was much thicker and tasted better then the shake mixes. I just ordered WonderSlim and am on day 2, and so far things taste much better than Medifast, but you still know you are eating diet food
I like that the WonderSlim plan is not so ridged as far as carbs go, but there are plenty of people out there that do WonderSlim and count carbs.
Please also know that Medifast is basically a low-carb, high protein liquid diet, although you can have bars and one "lean and green" meal per day. WonderSlim is also a basically a low-carb, high protein liquid diet, but you can have their pasta on their plan and fruit in addition to what you can have on Medifast.
If you want to go the Medifast route, I have heard that you can call Medifast and order individual packets for $2.50 each, which honestly isn't much more than it costs if you buy a 7 pack, so you might want to do that. On other option is you can just buy 2 weeks worth of food and try it out for 2 weeks, after the first week you should know if you can stick with it or not and have time to place another order so you don't run out. There are coupon codes out there for $25 off a $150 purchase, so what I did recently is I ordered just over $150 worth of bars, used the coupon code and shipping was around $9 (I really like the mint maintenance bars and am going to incorporate them into my low calorie diet).
What I am personally doing right now is I ordered a number of things from DietsDirect and the bars from Medifast (both crunch bars and maintenance bars) and am watching my calories and trying to stick to 1200 calories per day. I am a picky eater, and just couldn't do Medifast again, especially because I love carbs, but all of the protein and fiber in these supplements do help to keep you fuller longer, hence making it easier to stick to 1200 calories/day.
If after reading this you think that Medifast/WonderSlim is not for you, you might want to look into Jenny Craig. It is along the same lines as what you are doing now, but it tastes much better. Good luck!