MMMMMMMMM, 5megpix.
Just how many megpix can you post? A 640x480 pic is usually excellent for the internet if that's the objective and that may less than 2mp.
However, is you want to enlarge the pic or make a decent print it would be marginal at best.
the 3mp may be a good choice for a modest budget as prints up to 5x7 should be very acceptable and 8x10 are often quite good also. But enlarging the pic decreases the pixels and thus the quality. But a 3mp pic often times is too large for the Internet postings and the pixels often are reduced anyway.
With 5mp you have more to work with when you enlarge of edit. But you still have to address the size of the picture to Email or post.
To compare picture sizes some common sizes are 640 × 480 = 307,200 pixels or 0.3 megapixels which is plenty good for the internet and most Emails, 1.3 Megapixels = 1280x1024, 3.1 Megapixels = 2048x1536, 5.2 Megapixels = 2560x2048, etc.
As you can see the picture gets larger.
.
And go for a good optical zoom. There are some good ones of up to 10x with image stabilization. If you have a computer to edit your pics stay away from the "digital" zooms as the ones I am familiar with reduce the mp of the pic being
