First things first, this is based on use with iPad. If you have an iPhone or iPod the decision is made for you. You already knew that right?
Both apps are are modular workspace environments. Both work well on iPad. They look, sound, and feel similar.
To the left we have Table Top. To the right obviously is Rhythm Studio.
The similarities are stunning.
So I will try to focus on the most significant differences.
Table Top is $4.99 (US)
Rhythm Studio is $.99 (US)
Table top is a bit more developed at the moment with a bunch more features and functions. It has Audio Paste. It also offers more modules (15) right off the bat included in the basic starter set. Table Top offers more additional modules via In App Purchase. At first the FX were horribly over priced at $4.99 each! Ouch, that’s gonna add up fast. However they lowered the FX IAP prices to $.99 for the time being. The other IAP mods range from $2.99 to $9.99 with more promised to be added.
Rhythm Studio at the moment is $.99, has 5 modules (counting the FX and mixer as one mod), no ACP support right now, but it is coming. Similarly lots more modules promised, but the similarity ends here in that they will all be for FREE in future updates.
I found both to have nice audio quality, easy to use and understand. Both really captured the 80s nostalgic feel excellently.
I say if you’re on the fence trying to decide which is best for you, ask yourself this. Will either replace my existing iOS music “studio” set up or collection of apps? Do either do anything I cannot already do, or better? If you answer honestly NO, then why are you even still reading?
If you come back with a YES to those questions then proceed to the next questions. How much am I willing to commit financially? Am I OK with the future of IAPs to further my virtual modular workspace as new mods are added?
Did you answer YES to both? Congrats you chose Table Top.
Did you answer NO? Congratulations you just chose Rhythm Studio.
Either way you’re getting something pretty cool for making iOS music, if you are going for that 80s feel.
SmiteMatter iOS Music 
PS This is not a review.
I have the feeling Rhythm Studio may quickly find a niche providing emulations of classic analog gear. Pulsecode are already in the process of bringing the WASP synth to Rhythm Studio to compliment their 303 and 808. That's gonna be fun to try 🙂
I'm really excited to see Wasp as well. I echo your enthusiasm 🙂
Well, Table Top prices have gone back up. Way up. Worth it? You tell me.