I'll also vote for Keil. In the last year I've done one major project with Keil and one major project in SDCC. Both worked, but the Keil product is much more polished. Obviously nearly, what, two decades of development and a significant price tag buys you something.

SDCC worked in the project that I used it in, but I did find myself having to jump through some hoops to get the compiler to do what I wanted it to; and at least once it did something that made no sense to me--so I had to jump through a hoop to make it not do that weird thing.

If you're new to the 8052 architecture, I'd recommend the Keil compiler if you have the budget for it. SDCC is getting better fast, but if I were new to the 8052 architecture, the "weird thing" I experienced with SDCC would've been enough to have me pulling my hair out wondering what was wrong with my code or the microcontroller.

I do think SDCC has gotten a lot better since it was first released and I hope there will be continued progress. But I wouldn't recommend it for someone new to the architecture for anything but the simplest and smallest prorams. Once you have more experience, SDCC isn't necessarily a bad choice. But by that time you probably already have Keil anyway and there's no reason to use SDCC if you already have paid for Keil.

Regards,
Craig Steiner