A micro ATX form factor motherboard which should suffice the needs for now. An MSI FM2-A55M-E33 is a good solution. It is a cheap mobo that comes with 2 DIMM slots that allow RAM expansion upto 32GB capable of supporting the 1600Mhz RAM modules we’ll have considered.
It also has a PCI Express x16 slot which would get our graphics card working too. This mobo can be got for around $50 which is a very decent buy.