We booked four as well.
Housesimple could not seem to book the time we wanted and kept returning an appointment for another time, then cancelling the one we'd chosen... we figured if their admin was that bad at the start, it wasn't a good sign.
Emoov - gave local agent wrong time, he then wanted us to enquire about his diary appointments with the admin team instead of doing it himself - sacked them off.
Local agent turned up 15 minutes late, provided a valuation calculated by adding xx% on to last year's prices with no other justification or explanation. Then did not send the valuation report.
In the end we chose Purple Bricks because the lady who came is an ex-EA manager locally and was the only one who had her sh*t together. She turned up on time, and she came to the valuation by looking at live and sold prices, examining the features in detail with us and looking at why things had/hadn't sold. We felt this was the most thorough approach and her valuation was roughly in line with the local EA firm.
The golden rule is not to go with the highest valuation but to get an average from all of them. Use the appointment to get a feel for how organised and punctual they are as well. If they are late/ crap with paperwork when trying to get your business, maybe they don't want it that much!
If you plan to invite an online agent, check the terms thoroughly when it comes to fees. Purple Bricks' fee is non-refundable and you have to pay extra for accompanied viewings. Also, you're paying mainly for the platform they offer whereas a local EA is probably more personally available to you.
Check Twitter/ Facebook as well as review websites.
If you aren't sure, go with an agent that does not tie you in to paying a fee if it doesn't sell (so that rules out Purple Bricks!)