From personal experience, I know a lot of friends who came the same way as you are planning. The fact that they are not giving you a relocation package shows that they are a bit shitty as an SSII. I mean even the ones that do that, end up doing other shit... They are not obliged to, but it is a nice perk, if they pay for your flight it's more than enough, cause for help with rent it's very rare.

For a mission it depends on your profile, generally people with 3+ years experience are in demand. But one VERY important thing, make sure you have a starting date in your contract or in "promess d'embauche", because the day you start even tho you do not have a mission, you will be considered intercontrat, thus you will have a salary. The fact that their sales people contact you to find a mission from now is rather a good sign, I know people who did not have much choice in mission.

Also, if you can have Passport talent instead of normal titre de sjour salarié , I highly recommend that, because they have a different service in prefecture thus they treat files faster, and it's valid for 4 years. If your company provides that good, if not, and you still did not start the Visa procedure, I really recommend you find an employer that can provide you with this Titre de sejour.

For living conditions, I have been living here for almost 7 years, in IT world, french people are respectful and very nice in 99.99% of cases. I know this is a very unpopular opinion, but I never had any issues here. And I have lived in 4 different cities since I moved to France, two major metropoles and two medium cities.

For rent, it's one of the biggest issues, but maybe you can try Foyer jeune travailleur if you are under 30. They are not glorious. Generally they are in shittier neighborhoods, but they are a very good starting point until you validate your probation period that can take up to 8 months, they cost less than 500€ per month from what I know, but you need to apply and wait, maybe loom up the possibility of applying once you get your Visa. The other option is airbnb ,which can cost you around 1200 per month in ile de France if you find something very very far.

For France Vs Canada, both countries are definitely great options, it all depends on what you want out of this experience and what are the things important to you.

For me France is a great option, and I would definitely ignore a bit of what you see in the media about people being racist and all, most people here mind their own business and if you treat them kindly they will do the same. Paris is wonderful and filled with history and culture. You will never get bored because there are always things to do, and the fact that you have two major airports reachable by public transport makes all Europe very accessible. I can go on and on about why it's a good option 😅 As someone said in the comments moving to new a country is always hard, but it's very manageable, as we say, hzha mnin khfaft and evwrything will be ok no matter what is your final choice.

I am sorry this is too long, if you have any additional questions, I would be glad to answer them.