Intel and AMD are not compatible, so you choose which ever way you want to go.
Intel is easier as all the chips from one generation will fit onto boards from the same generation.
AMD can be trickier to navigate as they have several chip families using different motherboard interfaces.
Unfortunately I'm not able to suggest anything as I'm not familiar with pricing in your country.
I can suggest, looking at your current system, that you look at something no less than a Core i3 CPU. You'll want a Core i5 or better if you can afford it, but a Core i3 is a good starting point.