I am interested about sound synthesis and music production. I came across max/msp and cubase and they seem to be the de facto standards in this field. I would like to have some recommendation about the two, their pros and cons and which one is better for sound synthesis rather than sequencing.
The two products are pretty different. Cubase is a DAW whose primary purpose is to sequence MIDI and manage digital audio. Max/MSP, meanwhile, is a modular programming environment for audio. DAWs like Cubase tend to arrange things on tracks with a timeline, and offer the ability to effect, modify, and edit those tracks. Max has everything in little modules that connect to each other to send messages back and forth. If you want "tracks," you'd have to build them in the environment.
It's pretty hard to say which one is "better" for synthesis. It will really depend on how you want to go about it. If you want to "use synthesizers," then what you really need is a synthesizer. You can get them as plugins for compatible hosts (Cubase hosts VST format, for example) or you can get a hardware one, or you can assemble one using something like Max. If you want to host one and manage its use, you'll probably have better luck with a DAW like Cubase. If you're interested in cobbling together interesting audio machines from basic parts, then you might enjoy Max/MSP. Both of them will give you a great education in audio design, although if you're also interested in production, I'd suggest learning a DAW first since a lot of advice you're likely to find, especially for recording and processing, will be oriented at a tool like that.
Don't limit yourself to just those two options though. The claim that they're "the de-facto standards" in their fields is dubious at best. There are lots of DAWs that all have their fans, although certain circles tend to prefer different ones. Likewise, there are lots of synthesis environments.
If they have free trials, you might want to give them a try and see what you can see. If they don't, find similar software so you can compare the basic workflows. REAPER is a DAW with a 30-day free trial, and Pure Data is a free modular environment like Max.