So to sum up requirements
other pic should:
1.) Should be pin-to-pin compatible with current pic so any user can exchange it easily
2.) Should be cheap
3.) Should have more FLASH (64K+ the bigger the better)
4.) Should have more RAM(the bigger the better
I did a parametric analysis of all the currently available PIC18 devices that fulfill "basic requirements" (pin compatible, has EEPROM, can self-program itself, more FLASH and RAM than PIC18F2525), and the following devices are possibly suitable:
The first two PICs we already discussed, and the last one is new to our discussion
Each of these PICs has strengths and weaknesses, and unfortunately there is no 'perfect' PIC which fulfills all the requirements in your list.
To make a choice, one would need to decide what is the highest priority requirement.
Here is a table of priorities and which PIC is suitable for that priority:
Maximum Flash - Choose PIC18LF2685 (~30MHz possible, 96KB Flash, 3328 bytes RAM, $5.87)
Maximum RAM - Choose PIC18LF2620 (~30MHz possible, 64KB Flash, 3968 bytes RAM, $4.06)
Maximum speed, lowest price - Choose PIC18F26K20 (64MHz possible, 64KB Flash, 3936 bytes RAM, $1.65)
If price and speed is no concern, then the PIC18F26K20 is no longer attractive, because the PIC18LF2620 is very similar, but has slightly more RAM.
If RAM is more important than Flash, then PIC18LF2620 or PIC18F26K20 is more attractive, depending on whether you prefer speed/price over slightly more RAM.
These are the best PICs for us, but in the end you can only decide after you have performed some evaluation, I hope it goes well
I'll get myself PIC18F28K20 also to be able to experiment
I'll also need some kind of pic programmer also I was thinking some cheep programmer from ebay recomendations are welcome. It would be nice if I could use some kind of debuger instead of just printf to serial. There are some kind of PIC debuggers ICD2 and ICD3 but I don't know they would work for minimig.
Make sure that you try to get free samples of PICs from Microchip. This is especially good if you are evaluating different devices
Regarding ICD2/ICD3/REAL ICE - these are great devices for in-circuit programming and debugging, but unfortuantely the Minimig hardware is not correctly setup for this. The PGD/PGC lines need to be dedicated for the ICSP header, but they seem to be used with the FPGA, and also you need a diode on MCLR to stop power from ICD from flowing into the board. So without hardware modifications, this won't be straightforward