If you get a good quality one they are great but there's a TON of shitty knock off chinese brands out there now. Things you want to look for is multi-wall/layer construction, at least double, most higher end boards are triple layer. It'll say something like "Triple Layer Composite PVC construction". Also consider what shape you want, wider ones are more stable and easier to balance on but a bit slower in the water, some are narrower and more 'sporty' so you move quicker but they're a lot harder to balance on. Some have pretty high weight ratings (500lbs+) so you can ride double or carry a bunch of gear. Mine has straps on the front and back so I can put a small backpack cooler with drinks/food on the back as well as clothes/speaker/etc up front.
irocker is a good brand, they have a range of boards and are a pretty good start. Also if the board supports it get an electric pump, makes it such a more enjoyable experience. You can pump it by hand but its ~10 minutes of pumping to fill the board versus get an electric pump and just turn it on and then start getting all your gear together. Usually by the time I've packed everything and had a snack its ready to go. So much nicer to not be exhausted before you start. Some places sell their own variant with the board otherwise you can get this one:
https://www.amazon.ca/gp/product/B07C5K7HFM
I have the blackfin model X and love it, though I bought it because everything else was out of stock in the summer due to craziness. The ircocker cruiser would be a good starting board and not break the bank as much.
https://irockersup.ca/paddleboards/
There's also a subreddit for them if you want to search other brand names:
https://www.reddit.com/r/Sup/ and YYC has a decently active FB group for iSUPs and they plan different trips throughout the summer so you can go as a group. (They mark the difficulty in the event too, a mix of newbie friendly and more experienced)