Looking for a good synth/keyboard

Abovel all I'm searching for a good keyboard, which means I put value on a wide range of clean and high level voices. Till now I dealed with a Yamaha PSR-48 which i guess is about 30 years old, therefore its actually missing any possibility connecting it with my other gear except MIDI and I cannot use its voices within my music. Additionally it would be great if that keyboard included some nice synthesizer.

I really appreciate some help

You don't say what your price range is. But personally I don't think you can go wrong with a Motif for an all in one solution. Some great sounds and there are additional ones available.
For ultra-realistic electric piano and organ/clavinet sounds - go for a Nord Electro
The Korg SV-1 also has some excellent sounds. I know people like to say you need to try them yourself but its not always easy to do so. I've owned an Electro, SV-1 and a motif so am happy to help with any questions you may have -I would say however that from what you're saying so far - Id go for a Yamaha Motif. You could get a good deal on an XS model if you look.

Z

Roland V-synth.... the original version is cheap right now.
You can make any sound with it.
Has a great model of the Juno analog sound, which you will not use because you will have fun making your own sound.
Well built.
There are lots of sounds in it and many free sound libraries out there for it.
It has a smart easy to understand layout.

Cheers,
Ian
There are still some brand new ones available. I have seen it go as low as $600 used.

After some research I put an eye on the Yamaha MO6 and the Roland Juno-G.

Has anyone of you used one of these two?

Still checking the V-Synth, though