If you've been lucky enough to work on pure agile software projects - consider yourself lucky instead of thinking that it is the norm.
I'm willing to bet that 80-85% of software projects are being run in an hybrid model. Pretty sure that number goes up even higher the larger the company becomes.
As for poopoo'ing waterfall and the thoughts that it can't work - I've worked in waterfall projects that worked and deliver better than some agile projects, and vice versa. Please don't be one of those annoying agile people that only signs the praises of agile, and think everything else is stupid.
1) Waterfall can be perfectly fine when you know all your requirements are fully and thoroughly defined upfront.
2) Of course, that's not the case in the vast majority of software development projects. When some of the requirements are unknown, or... shall we say, a little fluid, then agile is better able to cope.
This is better elementary commentary on the two methodologies. Actual efficiency of implementation of course depends on a host of other factors, that could equally affect a project (positively or negatively), but if we rule out those mediating factors, then the above two statements are at the heart of the difference between the application of these two methodologies.
Now in OP's case, " online surveys, e-learning, platform development, mobile development, WhatsApp solutions and a variety of other offerings to large corporate clients", well and fully defined requirements upfront doesn't seem to apply, hence agile probably be more appropriate.
And that's all I'm going to say on that.