16F883
Is essentially obsolete by now. PIC still makes a lot of chips that are no longer relevant for current design. They still sell them... at higher cost for the people that can't be bothered to migrate.
16F1936 has twice the stack depth, wider supply voltage range of operation, an extended instruction set, internall PLL, and a lot of additional features. And it's cheaper. This has been the case for at least the past 4-5 years, I think. It looks like 883 was one of the earlier chips to have been introduced with the new nanowatt technology. But right on the heels came many other advancements of the enhanced midrange chips. If you ever want to use an 8 bit PIC, use the microchip website tools to start looking for the best match. And if the part number doesn't start with a "1", doublecheck your selection.
One of the only places 883 appears to have an advantage is standy current of 50nA vs 100nA.
but it's a very old design then, they have no bothered to make anything better since.
The important thing for me, is the support and tools and supply chain. I could care less about innovation in the silicon. I want the parts to be available now and in the future, at a good price, in quantities small or large. I want complete and consistent documentation. I want a working tool chain and good, inexpensive or even free dev tools.
I honestly wouldn't be worried at all about AVR lineup. I think Microchip will improve AVR, if anything.