I my board I want to give user the facility to select whether to select between 3.3v or 5v logic for respective pins out of 8 in which this functionality available. please give your suggestion, what will be most suitable switch type for users?
I think you need to figure out what you really NEED vs what might be nice to have.
Things like whether the pins are bi-directional or if each individual pin is configurable (vs all 8 being the same) to connect a 5v MCU to either 3v or 5v logic and whether that is done in s/w or in h/w (automatically, or possibly even using jumpers).
These kinds of things can make a big difference in the final solution.
You need to define your requirements and then look at solutions for those requirements.
Just keep in mind that some of possibilities are more complex and costly than others to implement, and that is why you may need to try to limit your requirements to what is really needed vs what might be nice to have.
Another alternative is to simply switch to using 3v processors like espxxx modules and not use 5v AVRs.
They are cheap with gobs of resources and are much faster than the AVRs, they can control most 5v devices that are input only with no additional logic, and can use WiFi for additional communication for things like IoT applications or Home automation.
In terms of i/o pins, esp8266 modules don't have quite as many pins as say an AVR m328 but the esp32 does.
I guess my feeling is that if you are looking at using some kind of level shifting logic, why use 5v AVRs?
Do you really need 5v outputs and the drive capability provided by the AVR?
Why not jump to a 3v processor that offers more horsepower and resources and then do level shifting only if the i/o device needs to drive a signal back to the MCU.
These days, for all my personal projects, I'm using ESP based modules.
Not only do the ESP parts have lots more flash, RAM , and processing horsepower than the AVR but they also can have an on board filesystem for file storage, and don't require using the goofy proprietary AVR PROGMEM stuff for const data which makes tables and doing things like web services much simpler.
For my personal projects, I find that there are many things that are easy to do with ESP parts that are simply not possible with an AVR, particularly for the price point if doing network connectivity.