Even if your current rubber is not ITTF approved, it could help to let other people on this forum know what you are using and how you feel about them (too fast, too slow, too spinny, can't generate spin etc.)
About me: Beginner-intermediate, have used 7 premade rackets, all of which have ITTF-approved rubber but one. Currently playing with a custom setup.
I would suggest you stay away from MX-P, MX-S, and Hexer Duro, especially if you are a beginner.
Those rubber are built with a technology called tensor, which makes those rubber really bouncy.
Imagine tapping the ball and the ball fly away. Unless you have been playing for years and have excellent control, it would be best to stay away from them. There is no point to hitting a fast and spinny shot if it doesn't land on the table.
So what should you get?
I have not tried a lot of rubber, but here are some that you might be interested.
Yasaka Mark V:
I'm currently using it on my forehand. Considerably faster than most premade.
A whole lot spinnier than any premade rubber. This is a great rubber!
DHS Hurricane NEO 3:
Most people at my club are using this. Very spinny, but a little hard to use. (Most people at my club have table tennis training from China -- they're Chinese -- and so they can utilize this type of rubber well.) Also very cheap. If you have proper coaching you might be interested in this, or you can just ask your coach.
Xiom Vega Intro:
The fastest and most spinny of all the rubber I recommend.
My friend who has just started table tennis for 4 weeks thinks it's too bouncy. (Too fast)
It's one of the slower tensor, but unless you have proper coaching I would advice you to stay away from it.
I have some TT coaching, and sometimes I still find it too fast and hard to control when compared to my Mark V.
I'm currently using it on my backhand.
Palio CJ8000
Overall it's great. Not too fast. Spinny enough. Also very cheap.
There are also other great easy to use rubber that I haven't tried but are recommended like
Butterfly Sriver, Sapphira, Flextra
Xiom Musa
Donic Coppa, Vario
Stiga Mendo, Innova
Tibhar Rapid
Dawei 2008 XP <= Really cheap!
Gambler Reflectoid
Air Illumina
Other forum members might be able to tell you more about it.