Would you recommend getting a different type of weapons? In the moment I'm playing with dual-wield Dscims from last time I played on this account. Do I need to get the crush and OSRS Gold stab weapons? If yes, what would you recommend. Regarding Whips, do you think they are still favourable for now?
Also is god staff in general, the best right now? Should I bother adapting to the magic vulnerability of moster (earth, fire, water air)? Are prayers worth the effort and money nowadays considering the nerf to defend against prayers?
For starters, some general guidelines: I've told Dragonrider buys at half the ge price... But go for Bandos regardless. It's extremely cheap at present. (~6m on the Chestplate and the Tassets) Begin to work towards a Slayer helm, and try for an upgrade to T70 version, using your Slayer points.
To answer your question on stab, crush and slash weapons I'll explain how monster weaknesses work with an example. Steel dragons are vulnerable to Water spells. What this means is that you'll have the maximum accuracy when it comes to Magic (Water spells in particular.)
Similarly, if a monster cannot Crush for example, like Jadinkos that means melee is the fastest attack style against them, and Crush is the most efficient style. Contrarily, Range or Mage will suffer from lower accuracy. (Although at higher levels, your gear is typically good enough to ensure that you won't notice a significant distinction.)
In conclusion, keep your Dragon scimitars and avoid buying another melee weapon. They're enough for anything vulnerable to melee. As for dual wielding, as well as magic. It's likely that Cheap RS Gold you don't possess anti-fire potion, therefore, avoid dual wielding. Also, dual wielding allows the use of a shield and the Rejuvination/Resonance abilities.