Crop is fine. I used crop for years and decided to switch to full frame and have not looked back. Got all of the benefits I was looking for.
Better low light/noise performance (by a mile).
Increase image 'sharpness'. In a quote because I believe it is more than just the extra 1.6x lines in the image. Less noise reduction, gentler AA filter, sharpness even in camera that does the job with noticeably fewer artifacts, allowing for more sharpening to be applied if desired. I am trying to talk myself into upgrading 28-135 to the 24-105, but am consistently more than satisfied with the 28-135 on the FF. Having 24mm and an extra stop at the long end may be compelling, but IQ with my sample has all the detail and accurate color I need.
Just a cleanliness and relaxed nature of the images. I believe when the brain needs to work harder to interpret am image, we are a bit stressed looking at the image. This happens to me frequently with crop sensor images - much less so with FF images. Still happens - if a lens has busy bokeh, for example, it is uncomfortable for me to look at regardless of camera format.
And reduced DOF, when called for. This can be a mixed bag as I frequently have to consciously stop down a bit if I am shooting close to get enough DOF, but in the end, the narrower DOF option is a plus for me. Others my find the 'extra reach' of a crop sensor (only an issue if the lenses at hand require cropping if shot on FF) a preferred advantage.
In any case, choose what suits your needs and preferences. It is a tool for making images and suggest choosing the tool that works best for your style of photography and vision. For me, I more consistently make the images I want to make on FF (bags of detail yet a relaxed ease to the presentation and cleaner low light shots) but YMMV.