How long will you be there? For the last 5-7 years, I generally rent apartments for stays that are 3 nights or longer - I really like having cooking facilities (and laundry facilities can be helpful too). For shorter stays, I am OK with hotels and will happily take the extra service and (usually) better location. I stay away from AirBnB, though, because I'm not as happy with their user interface, and I subjectively believe I'm more likely to come across a scammer. My preference is for VRBO and their associated services (like HomeAway).
It's smart to be wary, so do your due diligence.......look for reviews and (like online reviews for most things) I recommend you toss out the top and bottom 10% as suspect. Communicate (email, phone, text, WhatsApp) with the owner or manager, and assess their responsiveness to your questions.
I stayed in a really nice apartment for 6 nights in Florence last October, and I also rented apartments in Rome, Genoa, and Padua. All were very good (or better), and I was very pleased with my experiences. I don't have specific recommendations, because the places I rented wouldn't be big enough for your group. (I chose a hotel in Naples because I'd read the city was kind of sketchy and I wanted the security of a 24 hour front desk, but it turns out I didn't feel uncomfortable or unsafe in the city at all.)
I have also rented apartments/cottages in New Zealand, Portugal, and Canada for short stays of 5-10 days, and had good experiences with them all.