I would talk to at least 3, but as many as necessary to get someone you are happy with. The main question I ask each one is about how they would value the house/what price they would market it at and what they factor into that, not so much because I need a valuation (already had a pretty good idea myself from my own research at this point) but more because a really good agent will give you a well reasoned, realistic, nuanced answer based on solid local knowledge, not just '3 beds round here go for x' but based on your street/specific area vs others, the condition of your house, development potential, the current market state and what clients they have on their books/looking. I am very suspicious of any agent who claims they'll sell it instantly for an inflated price (unless they can give me a very good rationale why that would be), that type tends to be bullshitters frankly, and if they bullshit you they will do the same to potential buyers which is very off-putting. There are some agents in my town I just won't view a house with as a buyer, ever, because I know they lie, oversell, hassle you etc., to get people through the door of viewings so it's just a waste of everyone's time. You definitely want to avoid that type!
But equally I don't like it when they have no ambition to achieve a good price whatsoever and just pitch at the lowest possible acceptable price to get a quick sale as that tells me they can't really be bothered to actively market the place in any way which is what I am paying them for after all...
I like an agent to question me on my circumstances, why and where we are moving to etc., so as to be able to give me a sensible marketing strategy with a 3 point price estimate, low price for quick sale, middle price and high/ambitious price if we are prepared to wait, and have a bit of a discussion on where in that range we should put the asking price.
I always look at prior examples of their adverts/photos and ask their advice on how we should 'stage' /dress the property for pics. Again I can get that advice elsewhere but I think how they reply to that question says a lot about their attitude and experience. If they can't even muster a 'tidy up the garden and hide the clutter in the sitting room' type response then I know they are no good.
Generally I like to feel they are a good (but not pushy) salesperson, don't need gushing compliments about the house but do need some enthusiasm shown, if anything I like them to be (constructively!) honest about any challenges they envision with selling it, I like to feel I can trust them to be honest and open, again both with me and potential buyers.
Ask about how they manage viewings, each agent is slightly different here and some are more flexible than others about how much notice they like to give, whether they like to hold keys and let themselves in for viewings even if you are out (which may or may not be what you want), what times they will do viewings at, weekends etc., and whether they will sometimes ask you to show someone around without an agent present. Ask what their views are on whether you should always, always take the kids, dogs etc out for viewings or whether they think it's acceptable to sometimes show people around with the family in the house (IMO the correct answer is it's always better to take the kids away but they understand and will work around family life and won't expect to be able to show up at 8am on a saturday morning to a show-home clean house with no children or toys in it, or at least not without giving you plenty of notice, but you may have your own views on that - esp given current circumstances which obviously play into how viewings work).