You can't get much out of your default router. It is always recommended to invest on a third-party router. Brand varies as well as their features.

The archer c1200 is a good router, no doubt in that, it is just the firmware is so buggy that causes the router to undergo its kernel panic session that causes the router to freeze and reboot. If the hardware is superior and the code of execution is weak, then the hardware has to follow the rules set by the code of execution. From my own personal experience, I've used both DIR850L and C1200. Both performs slightly similar except one with visible antennas and another doesn't. However it is recommended NOT to use any routers given by the ISPs especially with those router specially-coded under the supervision of TM or any other ISPs.

Owning a vpn service don't ensure that you're safe in the online world my friend. There are a lot of security measures should be taken apart from owning a vpn service. If you're using an ISP router that has poor security in it, then you're a goner. Remember how a few hackers get busted in the recent years? Are you confident your VPN provider able to protect you?

If you're using speed below than 500Mbps, Mikrotik would be fine. Above 800Mbps you will be needing a higher end mikrotik router or an ubiquiti. Do note that, you will be needing to understand a few programming-commands required to alter the settings of the router to fit your needs that won't be made publicly available. Usually those who own these type of routers often power users who wish to get more control over their networking gear. Cheapest would be Mikrotik around RM270 and max can go up to RM2k and above.

Another best solution is to own a consumer-grade router that gives you over 50% control such as from ASUS with broadcom chipset since it is supported by Asus-Merlin fw. I am not affiliated with ASUS, but so far, they are recommended (ASUS with Broadcom chipset) by me. However I am not keen to use their features that requires data since I am more into a privacy-driven dude, thus lead me to opt for an prosumer-based router that gives me 100% of control towards my router.

Sorry for the delay in responding. RB750Gr3. You can refer here. My bad, the price is RM280 and not RM270. Two years back, I bought the same unit for RM260 at lelong.
Are you still using the model?